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Odom J, Bacino CA, Karaviti LP, Bi W, Hoyos-Martinez A. Intrafamilial phenotypic heterogeneity in siblings with pseudohypoparathyroidism 1B due to maternal STX16 deletion. J Pediatr Endocrinol Metab 2024; 37:84-89. [PMID: 38095637 DOI: 10.1515/jpem-2023-0249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 11/15/2023] [Indexed: 01/10/2024]
Abstract
OBJECTIVES Pseudohypoparathyroidism (PHP1B) is most commonly caused by epigenetic defects resulting in loss of methylation at the GNAS locus, although deletions of STX16 leading to GNAS methylation abnormalities have been previously reported. The phenotype of this disorder is variable and can include hormonal resistances and severe infantile obesity with hyperphagia. A possible time relationship between the onset of obesity and endocrinopathies has been previously reported but remains unclear. Understanding of the condition's natural history is limited, partly due to a scarcity of literature, especially in children. CASE PRESENTATION We report three siblings with autosomal dominant PHP1B caused by a deletion in STX16 who presented with early childhood onset PTH-resistance with normocalcemia with a progressive nature, accompanied by TSH-resistance and severe infantile obesity with hyperphagia in some, not all of the affected individuals. CONCLUSIONS PHP1B from a STX16 deletion displays intrafamilial phenotypic variation. It is a novel cause of severe infantile obesity, which is not typically included in commercially available gene panels but must be considered in the genetic work-up. Finally, it does not seem to have a clear time relationship between the onset of obesity and hormonal resistance.
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Affiliation(s)
- John Odom
- Department of Molecular and Human Genetics, Baylor College of Medicine, Texas Children's Hospital, Houston, TX, USA
| | - Carlos A Bacino
- Department of Molecular and Human Genetics, Baylor College of Medicine, Texas Children's Hospital, Houston, TX, USA
| | - Lefkothea P Karaviti
- Department of Pediatrics, Division of Pediatric Diabetes and Endocrinology, Baylor College of Medicine, Texas Children's Hospital, Houston, TX, USA
| | - Weimin Bi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Texas Children's Hospital, Houston, TX, USA
- Baylor Genetics, Houston, TX, USA
| | - Alfonso Hoyos-Martinez
- Department of Pediatrics, Division of Pediatric Diabetes and Endocrinology, Baylor College of Medicine, Texas Children's Hospital, Houston, TX, USA
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Huang S, He Y, Lin X, Sun S, Zheng F. Clinical and genetic analysis of pseudohypoparathyroidism complicated by hypokalemia: a case report and review of the literature. BMC Endocr Disord 2022; 22:98. [PMID: 35410271 PMCID: PMC9004107 DOI: 10.1186/s12902-022-01011-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 03/30/2022] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Pseudohypoparathyroidism (PHP) encompasses a highly heterogenous group of disorders, characterized by parathyroid hormone (PTH) resistance caused by mutations in the GNAS gene or other upstream targets. Here, we investigate the characteristics of a female patient diagnosed with PHP complicated with hypokalemia, and her family members. CASE PRESENTATION AND GENE ANALYSIS A 27-year-old female patient occasionally exhibited asymptomatic hypocalcemia and hypokalemia during her pregnancy 1 year ago. Seven months after delivery, she experienced tetany and dysphonia with diarrhea. Tetany symptoms were relieved after intravenous calcium gluconate supplementation and she was then transferred to our Hospital. Laboratory assessments of the patient revealed hypokalemia, hypocalcemia and hyperphosphatemia despite elevated PTH levels. CT scanning of the brain revealed globus pallidus calcification. Possible mutations in GNAS and hypokalemia related genes were identified using WES, exon copies of STX16 were analized by MLPA and the methylation status of GNAS in three differential methylated regions (DMRs) was analyzed by methylation-specific polymerase chain reaction, followed by confirmation with gene sequencing. The patient was clinically diagnosed with PHP-1b. Loss of methylation in the A/B region and hypermethylation in the NESP55 region were detected. No other mutations in GNAS or hypokalemia related genes and no deletions of STX16 exons were detected. A negative family history and abnormal DMRs in GNAS led to a diagnosis of sporadic PHP-1b of the patient. CONCLUSIONS Hypokalemia is a rare disorder associated with PHP-1b. Analysis of genetic and epigenetic mutations can aid in the diagnosis and accurate subtyping of PHP.
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Affiliation(s)
- Shaohan Huang
- Department of endocrinology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yingzi He
- Department of endocrinology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xihua Lin
- Department of endocrinology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Shuiya Sun
- Department of endocrinology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Fenping Zheng
- Department of endocrinology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
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Kiuchi Z, Reyes M, Brickman AS, Jüppner H. A Distinct Variant of Pseudohypoparathyroidism (PHP) First Characterized Some 41 Years Ago Is Caused by the 3-kb STX16 Deletion. JBMR Plus 2021; 5:e10505. [PMID: 34258502 PMCID: PMC8260810 DOI: 10.1002/jbm4.10505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 11/10/2022] Open
Abstract
In 1980, Farfel and colleagues (NEJM, 1980;303:237-42) provided first evidence for two distinct variants of pseudohypoparathyroidism (PHP) that present with hypocalcemia and impaired parathyroid hormone (PTH)-stimulated urinary cAMP and phosphate excretion, either in the presence or absence of Albright's hereditary osteodystrophy (AHO). An "abnormal allele" and an "unexpressed allele" were considered as underlying defects, predictions that turned out to be correct for both forms of PHP. Patients affected by the first variant (now referred to as PHP1A) were later shown to be carriers of inactivating mutations involving the maternal GNAS exons encoding Gsα. Patients affected by the second variant (now referred to as PHP1B) were shown in the current study to carry a maternal 3-kb STX16 deletion, the most frequent cause of autosomal dominant PHP1B, which is associated with loss of methylation at GNAS exon A/B that reduces or abolishes maternal Gsα expression. However, the distinct maternal mutations leading to either PHP1A or PHP1B are disease-causing only because paternal Gsα expression in the proximal renal tubules is silenced, ie, "unexpressed." Our findings resolve at the molecular level carefully conducted investigations reported some 41 years ago that had provided first clues for the existence of two distinct PHP variants. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Zentaro Kiuchi
- Endocrine Unit Massachusetts General Hospital and Harvard Medical School Boston MA USA
| | - Monica Reyes
- Endocrine Unit Massachusetts General Hospital and Harvard Medical School Boston MA USA
| | - Arnold S Brickman
- School of Medicine University of California Los Angeles Los Angeles CA USA
| | - Harald Jüppner
- Endocrine Unit Massachusetts General Hospital and Harvard Medical School Boston MA USA.,Pediatric Nephrology Unit Massachusetts General Hospital and Harvard Medical School Boston MA USA
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Abstract
Pseudohypoparathyroidism (PHP) and pseudopseudohypoparathyroidism (PPHP) are caused by mutations and/or epigenetic changes at the complex GNAS locus on chromosome 20q13.3 that undergoes parent-specific methylation changes at several differentially methylated regions (DMRs). GNAS encodes the alpha-subunit of the stimulatory G protein (Gsα) and several splice variants thereof. PHP type Ia (PHP1A) is caused by heterozygous inactivating mutations involving the maternal exons 1-13. Heterozygosity of these maternal GNAS mutations cause PTH-resistant hypocalcemia and hyperphosphatemia because paternal Gsα expression is suppressed in certain organs thus leading to little or no Gsα protein in the proximal renal tubules and other tissues. Besides biochemical abnormalities, PHP1A patients show developmental abnormalities, referred to as Albright's hereditary osteodystrophy (AHO). Some, but not all of these AHO features are encountered also in patients affected by PPHP, who carry paternal Gsα-specific mutations and typically show no laboratory abnormalities. Autosomal dominant PHP type Ib (AD-PHP1B) is caused by heterozygous maternal deletions within GNAS or STX16, which are associated with loss of methylation at the A/B DMR alone or at all maternally methylated GNAS exons. Loss of methylation of exon A/B and the resulting biallelic expression of A/B transcript reduces Gsα expression thus leading to hormonal resistance. Epigenetic changes at all differentially methylated GNAS regions are also observed in sporadic PHP1B, which is the most frequent PHP1B variant. However, this disease variant remains unresolved at the molecular level, except for rare cases with paternal uniparental isodisomy or heterodisomy of chromosome 20q (patUPD20q).
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Affiliation(s)
- Harald Jüppner
- Endocrine Unit, Department of Medicine and Pediatric Nephrology Unit, Department of Pediatrics, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Correspondence: Harald Jüppner, MD, Endocrine Unit, Thier 10, 50 Blossom Street, Massachusetts General Hospital, Boston, MA 02114, USA.
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Luo D, Qi X, Liu L, Su Y, Fang L, Guan Q. Genetic and Epigenetic Characteristics of Autosomal Dominant Pseudohypoparathyroidism Type 1B: Case Reports and Literature Review. Horm Metab Res 2021; 53:225-235. [PMID: 33513624 DOI: 10.1055/a-1341-9891] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Autosomal dominant pseudohypoparathyroidism 1B (AD-PHP1B) is a rare endocrine and imprinted disorder. The objective of this study is to clarify the imprinted regulation of the guanine nucleotide binding-protein α-stimulating activity polypeptide 1 (GNAS) cluster in the occurrence and development of AD-PHP1B based on animal and clinical patient studies. The methylation-specific multiples ligation-dependent probe amplification (MS-MLPA) was conducted to detect the copy number variation in syntaxin-16 (STX16) gene and methylation status of the GNAS differentially methylated regions (DMRs). Long-range PCR was used to confirm deletion at STX16 gene. In the first family, DNA analysis of the proband and proband's mother revealed an isolated loss of methylation (LOM) at exon A/B and a 3.0 kb STX16 deletion. The patient's healthy grandmother had the 3.0 kb STX16 deletion but no epigenetic abnormality. The patient's healthy maternal aunt showed no genetic or epigenetic abnormality. In the second family, the analysis of long-range PCR revealed the 3.0 kb STX16 deletion for the proband but not her children. In this study, 3.0 kb STX16 deletion causes isolated LOM at exon A/B in two families, which is the most common genetic mutation of AD-PHP1B. The deletion involving NESP55 or AS or genomic rearrangements of GNAS can also result in AD-PHP1B, but it's rare. LOM at exon A/B DMR is prerequisite methylation defect of AD-PHP1B. STX16 and NESP55 directly control the imprinting at exon A/B, while AS controls the imprinting at exon A/B by regulating the transcriptional level of NESP55.
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Affiliation(s)
- Dandan Luo
- Department of Endocrinology and Metabolism, Shandong University, Jinan, Shandong, China
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
| | - Xiangyu Qi
- Department of Endocrinology and Metabolism, Shandong University, Jinan, Shandong, China
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
| | - Luna Liu
- Department of Endocrinology and Metabolism, Shandong University, Jinan, Shandong, China
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
| | - Yu Su
- Department of Endocrinology and Metabolism, Shandong University, Jinan, Shandong, China
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
| | - Li Fang
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
| | - Qingbo Guan
- Department of Endocrinology and Metabolism, Shandong University, Jinan, Shandong, China
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
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Kiuchi Z, Reyes M, Jüppner H. Preferential Maternal Transmission of STX16-GNAS Mutations Responsible for Autosomal Dominant Pseudohypoparathyroidism Type Ib (PHP1B): Another Example of Transmission Ratio Distortion. J Bone Miner Res 2021; 36:696-703. [PMID: 33247854 DOI: 10.1002/jbmr.4221] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 11/11/2020] [Accepted: 11/19/2020] [Indexed: 01/13/2023]
Abstract
Preferential transmission of a genetic mutation to the next generation, referred to as transmission ratio distortion (TRD), is well established for several dominant disorders, but underlying mechanisms remain undefined. Recently, TRD was reported for patients affected by pseudohypoparathyroidism type Ia or pseudopseudohypoparathyroidism. To determine whether TRD is observed also for autosomal dominant pseudohypoparathyroidism type Ib (AD-PHP1B), we analyzed kindreds with the frequent 3-kb STX16 deletion or other STX16/GNAS mutations. If inherited from a female, these genetic defects lead to loss-of-methylation at exon A/B alone or at all three differentially methylated regions (DMR), resulting in parathyroid hormone (PTH)-resistant hypocalcemia and hyperphosphatemia and possibly resistance to other hormones. In total, we investigated 212 children born to 80 females who are unaffected carriers of a STX16/GNAS mutation (n = 47) or affected by PHP1B (n = 33). Of these offspring, 134 (63.2%) had inherited the genetic defect (p = .00012). TRD was indistinguishable for mothers with a STX16/GNAS mutation on their paternal (unaffected carriers) or maternal allele (affected). The mechanisms favoring transmission of the mutant allele remain undefined but are likely to include abnormalities in oocyte maturation. Search for mutations in available descendants of males revealed marginally significant evidence for TRD (p = .038), but these analyses are less reliable because many more offspring of males than females with a STX16/GNAS mutation were lost to follow-up (31 of 98 versus 6 of 218). This difference in follow-up is probably related to the fact that inheritance of a mutation from a male does not have clinical implications, whereas inheritance from an affected or unaffected female results in PHP1B. Lastly, affected PHP1B females had fewer descendants than unaffected carriers, but it remains unclear whether abnormal oocyte development or impaired actions of reproductive hormones are responsible. Our findings highlight previously not recognized aspects of AD-PHP1B that are likely to have implications for genetic testing and counseling. © 2020 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Zentaro Kiuchi
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Monica Reyes
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Harald Jüppner
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.,Pediatric Nephrology Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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Yang Y, Chu X, Nie M, Song A, Jiang Y, Li M, Xia W, Xing X, Wang O. A novel long-range deletion spanning STX16 and NPEPL1 causing imprinting defects of the GNAS locus discovered in a patient with autosomal-dominant pseudohypoparathyroidism type 1B. Endocrine 2020; 69:212-219. [PMID: 32337648 DOI: 10.1007/s12020-020-02304-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Accepted: 04/04/2020] [Indexed: 10/24/2022]
Abstract
BACKGROUND Pseudohypoparathyroidism (PHP) is a rare disorder characterized by hypocalcemia, hyperphosphatemia, and resistance to parathyroid hormone (PTH). According to different GNAS mutations, PHP is divided into several subtypes, among which autosomal-dominant PHP1B (AD-PHP1B) is caused by STX16 deletion and epigenetic alteration of GNAS. Although the deletion of STX16 exons 2-6 is commonly observed, other mutations involving STX16 can also result in AD-PHP1B. MATERIALS AND METHODS The clinical information of a 38-year-old male PHP patient was collected. The genomic DNA from peripheral blood cells was extracted for genetic analysis of GNAS and upstream STX16 by methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) and whole-exome sequencing (WES). Sanger sequencing was performed to verify the break point of the novel long-range deletion. RESULTS The patient's medical history of tetany and seizure as well as laboratory examination showing hypocalcemia and elevated PTH levels indicated the diagnosis of PHP. The results of MS-MLPA showed loss of methylation of GNAS A/B:TSS-DMR and half-reduced copy number of STX16 exon 1-9, which revealed the subtype of AD-PHP1B. Furthermore, the WES study displayed a 87.5 kb missing upstream of GNAS. A 87.5 kb deletion spanning STX16 and NPEPL1 together with an insertion of 28 bp of unknown origin was verified by PCR along with Sanger sequencing. CONCLUSIONS A novel deletion of 87.5 kb spanning STX16 and NPEPL1 was discovered in an AD-PHP1B patient, which provides new information on molecular defects leading to AD-PHP1B.
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Affiliation(s)
- Yi Yang
- Key Laboratory of Endocrinology of the Ministry of Health, Department of Endocrinology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China
| | - Xueying Chu
- Key Laboratory of Endocrinology of the Ministry of Health, Department of Endocrinology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China
| | - Min Nie
- Key Laboratory of Endocrinology of the Ministry of Health, Department of Endocrinology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China
| | - An Song
- Key Laboratory of Endocrinology of the Ministry of Health, Department of Endocrinology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China
| | - Yan Jiang
- Key Laboratory of Endocrinology of the Ministry of Health, Department of Endocrinology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China
| | - Mei Li
- Key Laboratory of Endocrinology of the Ministry of Health, Department of Endocrinology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China
| | - Weibo Xia
- Key Laboratory of Endocrinology of the Ministry of Health, Department of Endocrinology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China
| | - Xiaoping Xing
- Key Laboratory of Endocrinology of the Ministry of Health, Department of Endocrinology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China
| | - Ou Wang
- Key Laboratory of Endocrinology of the Ministry of Health, Department of Endocrinology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China.
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Chen CP, Kuo YL, Chern SR, Wu PS, Chen SW, Wu FT, Chen LF, Wang W. Prenatal diagnosis of low-level mosaic trisomy 20 by amniocentesis in a pregnancy with a favorable outcome. Taiwan J Obstet Gynecol 2020; 59:327-330. [PMID: 32127159 DOI: 10.1016/j.tjog.2020.01.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/16/2019] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE We present prenatal diagnosis of low-level mosaic trisomy 20 by amniocentesis in a pregnancy with a favorable outcome. CASE REPORT A 35-year-old woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 47,XX,+20[8]/46,XX[23]. The parental karyotypes were normal, and prenatal ultrasound findings were unremarkable. Repeat amniocentesis performed at 20 weeks of gestation revealed a karyotype of 47,XX,+20[2]/46,XX[19]. Simultaneous molecular cytogenetic tests using uncultured amniocytes revealed no genomic imbalance in array comparative genomic hybridization (aCGH) analysis and a mosaic level of 14.3% (15/105 cells) in interphase fluorescence in situ hybridization (FISH) analysis. Polymorphic DNA marker analysis using the DNAs extracted from uncultured amniocytes and parental bloods excluded uniparental disomy 20. At 39 weeks of gestation, a phenotypically normal 3580-g female baby was delivered without any structural abnormality. The neonate was doing well at age two years during postnatal follow-ups. Her psychomotor development was normal. Interphase FISH analysis of urinary cells revealed no trisomy 20 signals in 45/45 urinary cells. The peripheral blood had a karyotype of 46,XX in 40/40 lymphocytes. CONCLUSION Fetuses with low-level mosaic trisomy 20 at amniocentesis can have a favorable outcome. Molecular cytogenetic analysis on uncultured amniocytes is useful for confirmatory diagnosis of the mosaic level in case of mosaic trisomy 20 at amniocentesis with different mosaic levels at different amniocenteses.
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Affiliation(s)
- Chih-Ping Chen
- Department of Obstetrics and Gynecology, MacKay Memorial Hospital, Taipei, Taiwan; Department of Medical Research, MacKay Memorial Hospital, Taipei, Taiwan; Department of Biotechnology, Asia University, Taichung, Taiwan; School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan; Institute of Clinical and Community Health Nursing, National Yang-Ming University, Taipei, Taiwan; Department of Obstetrics and Gynecology, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
| | - Yu-Ling Kuo
- Department of Obstetrics and Gynecology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Schu-Rern Chern
- Department of Medical Research, MacKay Memorial Hospital, Taipei, Taiwan
| | | | - Shin-Wen Chen
- Department of Obstetrics and Gynecology, MacKay Memorial Hospital, Taipei, Taiwan
| | - Fang-Tzu Wu
- Department of Obstetrics and Gynecology, MacKay Memorial Hospital, Taipei, Taiwan
| | - Li-Feng Chen
- Department of Obstetrics and Gynecology, MacKay Memorial Hospital, Taipei, Taiwan
| | - Wayseen Wang
- Department of Medical Research, MacKay Memorial Hospital, Taipei, Taiwan; Department of Bioengineering, Tatung University, Taipei, Taiwan
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Chen CP, Lin YH, Chern SR, Wu PS, Chen SW, Wu FT, Lee MS, Chen YY, Wang W. Cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes in mosaic double trisomy involving trisomy 7 and trisomy 20 (48,XY,+7,+20) at amniocentesis. Taiwan J Obstet Gynecol 2020; 59:146-149. [DOI: 10.1016/j.tjog.2019.11.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/16/2019] [Indexed: 10/25/2022] Open
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Han SR, Lee YA, Shin CH, Yang SW, Lim BC, Cho TJ, Ko JM. Clinical and Molecular Characteristics of GNAS Inactivation Disorders Observed in 18 Korean Patients. Exp Clin Endocrinol Diabetes 2019; 129:118-125. [DOI: 10.1055/a-1001-3575] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Abstract
Background The GNAS gene on chromosome 20q13.3 is a complex, imprinted locus regulated in a tissue-specific manner. GNAS inactivation disorders are a heterogeneous group of rare disorders caused by mutations and methylation defects. These are divided into pseudohypoparathyroidism (PHP) types 1A and 1B, pseudo-pseudohypoparathyroidism (PPHP), and progressive osseous heteroplasia (POH), depending on the presence or absence of hormone resistance, Albright’s hereditary osteodystrophy (AHO), and ectopic ossification.
Methods This study analyzed the clinical characteristics and molecular genetic backgrounds of 18 Korean patients from 16 families with a genetically confirmed GNAS defect. Auxological parameters, AHO phenotypes, types of hormonal resistance, family history, and molecular genetic disturbances were reviewed retrospectively.
Results Nine (90%) patients with PHP1A showed resistance to parathyroid hormone (PTH) and all patients showed elevated thyroid-stimulating hormone (TSH) levels at diagnosis. Eight (80%) patients were managed with levothyroxine supplementation. Three of six patients with PHP1B had elevated TSH levels, but none of whom needed levothyroxine medication. AHO features were absent in PHP1B. Patients with PPHP and POH did not show any hormone resistance, and both of them were born as small for gestational age. Among the 11 families with PHP1A, PPHP, and POH, eight different (three novel) mutations in the GNAS gene were identified. Among the six patients with PHP1B, two were sporadic cases and four showed isolated loss of methylation at GNAS A/B:TSS-DMR.
Conclusions Clinical and molecular characteristics of Korean patients with GNAS inactivation disorders were described in this study. Also, we reaffirmed heterogeneity of PHP, contributing to further accumulation and expansion of current knowledge of this complex disease.
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Affiliation(s)
- Sa Ra Han
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children’s Hospital, Seoul, Korea
| | - Young Ah Lee
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children’s Hospital, Seoul, Korea
| | - Choong-Ho Shin
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children’s Hospital, Seoul, Korea
| | - Sei-Won Yang
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children’s Hospital, Seoul, Korea
| | - Byung Chan Lim
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children’s Hospital, Seoul, Korea
| | - Tae-Joon Cho
- Department of Orthopaedics, Seoul National University College of Medicine, Seoul National University Children’s Hospital, Seoul, Korea
| | - Jung Min Ko
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children’s Hospital, Seoul, Korea
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Abstract
Pseudohypoparathyroidism (PHP) refers to a heterogeneous group of uncommon, yet related metabolic disorders that are characterized by impaired activation of the Gsα/cAMP/PKA signaling pathway by parathyroid hormone (PTH) and other hormones that interact with Gsa-coupled receptors. Proximal renal tubular resistance to PTH and thus hypocalcemia and hyperphosphatemia, frequently in presence of brachydactyly, ectopic ossification, early-onset obesity, or short stature are common features of PHP. Registries and large cohorts of patients are needed to conduct clinical and genetic research, to improve the still limited knowledge regarding the underlying disease mechanisms, and allow the development of novel therapies.
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Affiliation(s)
- Agnès Linglart
- INSERM-U1185, Paris Sud Paris-Saclay University, Bicêtre Paris Sud Hospital, 64 Gabriel Péri Street, 94270 Le Kremlin Bicêtre, France; APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Network OSCAR and 'Platform of Expertise Paris Sud for Rare Diseases, Bicêtre Paris Sud Hospital, 64 Gabriel Péri Street, 94270 Le Kremlin Bicêtre, France; APHP, Endocrinology and Diabetes for Children, Bicêtre Paris Sud Hospital, 64 Gabriel Péri Street, 94270 Le Kremlin Bicêtre, France.
| | - Michael A Levine
- Division of Endocrinology and Diabetes, Center for Bone Health, The Children's Hospital of Philadelphia, 3401 Civic Center Boulevard, Philadelphia, PA 19104, USA; Department of Pediatrics, University of Pennsylvania Perelman, School of Medicine, 3615 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Harald Jüppner
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, 50 Blossom street, Boston, MA 02114, USA; Pediatric Nephrology Unit, Massachusetts General Hospital, Harvard Medical School, 50 Blossom street, Boston, MA 02114, USA
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Mantovani G, Bastepe M, Monk D, de Sanctis L, Thiele S, Usardi A, Ahmed SF, Bufo R, Choplin T, De Filippo G, Devernois G, Eggermann T, Elli FM, Freson K, García Ramirez A, Germain-Lee EL, Groussin L, Hamdy N, Hanna P, Hiort O, Jüppner H, Kamenický P, Knight N, Kottler ML, Le Norcy E, Lecumberri B, Levine MA, Mäkitie O, Martin R, Martos-Moreno GÁ, Minagawa M, Murray P, Pereda A, Pignolo R, Rejnmark L, Rodado R, Rothenbuhler A, Saraff V, Shoemaker AH, Shore EM, Silve C, Turan S, Woods P, Zillikens MC, Perez de Nanclares G, Linglart A. Diagnosis and management of pseudohypoparathyroidism and related disorders: first international Consensus Statement. Nat Rev Endocrinol 2018; 14:476-500. [PMID: 29959430 PMCID: PMC6541219 DOI: 10.1038/s41574-018-0042-0] [Citation(s) in RCA: 180] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
This Consensus Statement covers recommendations for the diagnosis and management of patients with pseudohypoparathyroidism (PHP) and related disorders, which comprise metabolic disorders characterized by physical findings that variably include short bones, short stature, a stocky build, early-onset obesity and ectopic ossifications, as well as endocrine defects that often include resistance to parathyroid hormone (PTH) and TSH. The presentation and severity of PHP and its related disorders vary between affected individuals with considerable clinical and molecular overlap between the different types. A specific diagnosis is often delayed owing to lack of recognition of the syndrome and associated features. The participants in this Consensus Statement agreed that the diagnosis of PHP should be based on major criteria, including resistance to PTH, ectopic ossifications, brachydactyly and early-onset obesity. The clinical and laboratory diagnosis should be confirmed by a molecular genetic analysis. Patients should be screened at diagnosis and during follow-up for specific features, such as PTH resistance, TSH resistance, growth hormone deficiency, hypogonadism, skeletal deformities, oral health, weight gain, glucose intolerance or type 2 diabetes mellitus, and hypertension, as well as subcutaneous and/or deeper ectopic ossifications and neurocognitive impairment. Overall, a coordinated and multidisciplinary approach from infancy through adulthood, including a transition programme, should help us to improve the care of patients affected by these disorders.
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Affiliation(s)
- Giovanna Mantovani
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Endocrinology Unit, Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - David Monk
- Imprinting and Cancer Group, Cancer Epigenetic and Biology Program (PEBC), Institut d'Investigació Biomedica de Bellvitge (IDIBELL), Barcelona, Spain
| | - Luisa de Sanctis
- Pediatric Endocrinology Unit, Department of Public Health and Pediatric Sciences, University of Torino, Turin, Italy
| | - Susanne Thiele
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics, University of Lübeck, Lübeck, Germany
| | - Alessia Usardi
- APHP, Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Platform of Expertise Paris-Sud for Rare Diseases and Filière OSCAR, Bicêtre Paris Sud Hospital (HUPS), Le Kremlin-Bicêtre, France
- APHP, Endocrinology and diabetes for children, Bicêtre Paris Sud Hospital (HUPS), Le Kremlin-Bicêtre, France
| | - S Faisal Ahmed
- Developmental Endocrinology Research Group, School of Medicine, Dentistry and Nursing, University of Glasgow, Glasgow, UK
| | - Roberto Bufo
- IPOHA, Italian Progressive Osseous Heteroplasia Association, Cerignola, Foggia, Italy
| | - Timothée Choplin
- K20, French PHP and related disorders patient association, Jouars Pontchartrain, France
| | - Gianpaolo De Filippo
- APHP, Department of medicine for adolescents, Bicêtre Paris Sud Hospital (HUPS), Le Kremlin-Bicêtre, France
| | - Guillemette Devernois
- K20, French PHP and related disorders patient association, Jouars Pontchartrain, France
| | - Thomas Eggermann
- Institute of Human Genetics, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Francesca M Elli
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Endocrinology Unit, Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Kathleen Freson
- Department of Cardiovascular Sciences, Center for Molecular and Vascular Biology, Gasthuisberg, University of Leuven, Leuven, Belgium
| | - Aurora García Ramirez
- AEPHP, Spanish PHP and related disorders patient association, Huércal-Overa, Almería, Spain
| | - Emily L Germain-Lee
- Albright Center & Center for Rare Bone Disorders, Division of Pediatric Endocrinology & Diabetes, Connecticut Children's Medical Center, Farmington, CT, USA
- Department of Pediatrics, University of Connecticut School of Medicine, Farmington, CT, USA
| | - Lionel Groussin
- APHP, Department of Endocrinology, Cochin Hospital (HUPC), Paris, France
- University of Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Neveen Hamdy
- Department of Medicine, Division of Endocrinology and Centre for Bone Quality, Leiden University Medical Center, Leiden, Netherlands
| | - Patrick Hanna
- INSERM U1169, Bicêtre Paris Sud, Paris Sud - Paris Saclay University, Le Kremlin-Bicêtre, France
| | - Olaf Hiort
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics, University of Lübeck, Lübeck, Germany
| | - Harald Jüppner
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Peter Kamenický
- APHP, Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Platform of Expertise Paris-Sud for Rare Diseases and Filière OSCAR, Bicêtre Paris Sud Hospital (HUPS), Le Kremlin-Bicêtre, France
- APHP, Department of Endocrinology and Reproductive Diseases, Bicêtre Paris Sud Hospital (HUPS), Le Kremlin-Bicêtre, France
- INSERM U1185, Paris Sud - Paris Saclay University, Le Kremlin-Bicêtre, France
| | - Nina Knight
- UK acrodysostosis patients' group, London, UK
| | - Marie-Laure Kottler
- Department of Genetics, Reference Centre for Rare Disorders of Calcium and Phosphate Metabolism, Caen University Hospital, Caen, France
- BIOTARGEN, UNICAEN, Normandie University, Caen, France
| | - Elvire Le Norcy
- University of Paris Descartes, Sorbonne Paris Cité, Paris, France
- APHP, Department of Odontology, Bretonneau Hospital (PNVS), Paris, France
| | - Beatriz Lecumberri
- Department of Endocrinology and Nutrition, La Paz University Hospital, Madrid, Spain
- Department of Medicine, Autonomous University of Madrid (UAM), Madrid, Spain
- Endocrine Diseases Research Group, Hospital La Paz Institute for Health Research (IdiPAZ), Madrid, Spain
| | - Michael A Levine
- Division of Endocrinology and Diabetes and Center for Bone Health, Children's Hospital of Philadelphia and Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Outi Mäkitie
- Children's Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Regina Martin
- Osteometabolic Disorders Unit, Hormone and Molecular Genetics Laboratory (LIM/42), Endocrinology Division, Hospital das Clínicas HCFMUSP, Faculty of Medicine, University of Sao Paulo, Sao Paulo, Brazil
| | - Gabriel Ángel Martos-Moreno
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, CIBERobn, ISCIII, Madrid, Spain
- Department of Pediatrics, Autonomous University of Madrid (UAM), Madrid, Spain
- Endocrine Diseases Research Group, Hospital La Princesa Institute for Health Research (IIS La Princesa), Madrid, Spain
| | | | - Philip Murray
- Department of Paediatric Endocrinology, Royal Manchester Children's Hospital, Manchester University NHS Foundation Trust, Manchester, UK
| | - Arrate Pereda
- Molecular (Epi)Genetics Laboratory, BioAraba National Health Institute, Hospital Universitario Araba-Txagorritxu, Vitoria-Gasteiz, Alava, Spain
| | | | - Lars Rejnmark
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Rebecca Rodado
- AEPHP, Spanish PHP and related disorders patient association, Huércal-Overa, Almería, Spain
| | - Anya Rothenbuhler
- APHP, Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Platform of Expertise Paris-Sud for Rare Diseases and Filière OSCAR, Bicêtre Paris Sud Hospital (HUPS), Le Kremlin-Bicêtre, France
- APHP, Endocrinology and diabetes for children, Bicêtre Paris Sud Hospital (HUPS), Le Kremlin-Bicêtre, France
| | - Vrinda Saraff
- Department of Endocrinology and Diabetes, Birmingham Children's Hospital, Birmingham, UK
| | - Ashley H Shoemaker
- Pediatric Endocrinology and Diabetes, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Eileen M Shore
- Departments of Orthopaedic Surgery and Genetics, Center for Research in FOP and Related Disorders, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Caroline Silve
- APHP, Service de Biochimie et Génétique Moléculaires, Hôpital Cochin, Paris, France
| | - Serap Turan
- Department of Pediatrics, Division of Endocrinology and Diabetes, Marmara University, Istanbul, Turkey
| | | | - M Carola Zillikens
- Department of Internal Medicine, Bone Center Erasmus MC - University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Guiomar Perez de Nanclares
- Molecular (Epi)Genetics Laboratory, BioAraba National Health Institute, Hospital Universitario Araba-Txagorritxu, Vitoria-Gasteiz, Alava, Spain.
| | - Agnès Linglart
- APHP, Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Platform of Expertise Paris-Sud for Rare Diseases and Filière OSCAR, Bicêtre Paris Sud Hospital (HUPS), Le Kremlin-Bicêtre, France.
- APHP, Endocrinology and diabetes for children, Bicêtre Paris Sud Hospital (HUPS), Le Kremlin-Bicêtre, France.
- INSERM U1169, Bicêtre Paris Sud, Paris Sud - Paris Saclay University, Le Kremlin-Bicêtre, France.
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Abstract
GNAS is a complex imprinted gene encoding the alpha-subunit of the stimulatory heterotrimeric G protein (Gsα). GNAS gives rise to additional gene products that exhibit exclusively maternal or paternal expression, such as XLαs, a large variant of Gsα that shows exclusively paternal expression and is partly identical to the latter. Gsα itself is expressed biallelically in most tissues, although the expression occurs predominantly from the maternal allele in a small set of tissues, such as renal proximal tubules. Inactivating mutations in Gsα-coding GNAS exons are responsible for Albright's hereditary osteodystrophy (AHO), which refers to a constellation of physical and developmental disorders including obesity, short stature, brachydactyly, cognitive impairment, and heterotopic ossification. Patients with Gsα mutations can present with AHO in the presence or absence of end-organ resistance to multiple hormones including parathyroid hormone. Maternal Gsα mutations lead to AHO with hormone resistance (i.e. pseudohypoparathyroidism type-Ia), whereas paternal mutations cause AHO alone (i.e. pseudo-pseudohypoparathyroidism). Heterotopic ossification associated with AHO develops through intramembranous bone formation and is limited to dermis and subcutis. In rare cases carrying Gsα mutations, however, ossifications progress into deep connective tissue and skeletal muscle, a disorder termed progressive osseous heteroplasia (POH). Here I briefly review the genetic, clinical, and molecular aspects of these disorders caused by inactivating GNAS mutations, with particular emphasis on heterotopic ossification.
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Affiliation(s)
- Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, United States.
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Reyes M, Karaca A, Bastepe M, Gulcelik NE, Jüppner H. A novel deletion involving GNAS exon 1 causes PHP1A and further refines the region required for normal methylation at exon A/B. Bone 2017; 103:281-286. [PMID: 28711660 PMCID: PMC5943703 DOI: 10.1016/j.bone.2017.07.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Revised: 06/20/2017] [Accepted: 07/11/2017] [Indexed: 11/25/2022]
Abstract
GNAS exons 1-13 encode the biallelically expressed alpha-subunit of the stimulatory G protein (Gαs). Additional transcripts derived from this locus use alternative first exons that undergo parent-specific methylation, thus allowing transcription only from the non-modified allele. Pseudohypoparathyroidism type Ia (PHP1A) is characterized by Albright's Hereditary Osteodystrophy (AHO) and resistance to multiple hormones; this disorder is caused by maternal inactivating mutations involving Gαs exons. In contrast, pseudohypoparathyroidism type Ib (PHP1B) is characterized mostly by resistance to PTH and often mild TSH resistance, usually without AHO features. The autosomal dominant variant of PHP1B (AD-PHP1B) is caused by maternal deletions in GNAS or STX16 that reduce Gαs expression through loss-of-methylation at GNAS exon A/B alone or at multiple differentially methylated regions (DMR). Several large maternal deletions involve not only GNAS exons 1-13, but also one or several GNAS DMRs, thus causing PHP1A combined with apparent GNAS epigenetic changes that are indistinguishable from those observed in PHP1B. Some of these deletions include a large CpG island extending from exon A/B to the intron between GNAS exons 1 and 2, but there is no evidence for parent-specific exon 1 methylation. We now describe a family in which the female proband and her daughter presented with hypocalcemia, elevated PTH levels, shortened metacarpals, and obesity, but without obvious neurocognitive abnormalities. A maternally inherited 2015-bp deletion that includes GNAS exon 1 was identified thereby establishing the diagnosis of PHP1A. The centromeric deletion breakpoint is located 178bp upstream of exon 1, yet no methylation changes were observed at exon A/B. This novel deletion therefore refines further the region between exon A/B and exon 1 that is critical for establishing or maintaining normal methylation at GNAS exon A/B.
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Affiliation(s)
- Monica Reyes
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Anara Karaca
- Ankara Training and Research Hospital, Endocrinology and Metabolism, Ankara, Turkey
| | - Murat Bastepe
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Nese Ersoz Gulcelik
- Ankara Training and Research Hospital, Endocrinology and Metabolism, Ankara, Turkey
| | - Harald Jüppner
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA; Pediatric Nephrology Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
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15
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Bastepe M, Turan S, He Q. Heterotrimeric G proteins in the control of parathyroid hormone actions. J Mol Endocrinol 2017; 58:R203-R224. [PMID: 28363951 PMCID: PMC5650080 DOI: 10.1530/jme-16-0221] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 02/17/2017] [Indexed: 12/17/2022]
Abstract
Parathyroid hormone (PTH) is a key regulator of skeletal physiology and calcium and phosphate homeostasis. It acts on bone and kidney to stimulate bone turnover, increase the circulating levels of 1,25 dihydroxyvitamin D and calcium and inhibit the reabsorption of phosphate from the glomerular filtrate. Dysregulated PTH actions contribute to or are the cause of several endocrine disorders. This calciotropic hormone exerts its actions via binding to the PTH/PTH-related peptide receptor (PTH1R), which couples to multiple heterotrimeric G proteins, including Gs and Gq/11 Genetic mutations affecting the activity or expression of the alpha-subunit of Gs, encoded by the GNAS complex locus, are responsible for several human diseases for which the clinical findings result, at least partly, from aberrant PTH signaling. Here, we review the bone and renal actions of PTH with respect to the different signaling pathways downstream of these G proteins, as well as the disorders caused by GNAS mutations.
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Affiliation(s)
- Murat Bastepe
- Endocrine UnitDepartment of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Serap Turan
- Department of Pediatric EndocrinologyMarmara University School of Medicine, Istanbul, Turkey
| | - Qing He
- Endocrine UnitDepartment of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
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16
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Tafaj O, Jüppner H. Pseudohypoparathyroidism: one gene, several syndromes. J Endocrinol Invest 2017; 40:347-356. [PMID: 27995443 DOI: 10.1007/s40618-016-0588-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 11/25/2016] [Indexed: 01/04/2023]
Abstract
Pseudohypoparathyroidism (PHP) and pseudopseudohypoparathyroidism (PPHP) are caused by mutations and/or epigenetic changes at the complex GNAS locus on chromosome 20q13.3 that undergoes parent-specific methylation changes at several sites. GNAS encodes the alpha-subunit of the stimulatory G protein (Gsα) and several splice variants thereof. Heterozygous inactivating mutations involving the maternal GNAS exons 1-13 cause PHP type Ia (PHP1A). Because of much reduced paternal Gsα expression in certain tissues, such as the proximal renal tubules, thyroid, and pituitary, there is little or no Gsα protein in the presence of maternal GNAS mutations, thus leading to PTH-resistant hypocalcemia and hyperphosphatemia. When located on the paternal allele, the same or similar GNAS mutations are the cause of PPHP. Besides biochemical abnormalities, patients affected by PHP1A show developmental abnormalities, referred to as Albrights hereditary osteodystrophy (AHO). Some, but not all of these AHO features are encountered also in patients affected by PPHP, who typically show no laboratory abnormalities. Autosomal dominant PHP type Ib (AD-PHP1B) is caused by heterozygous maternal deletions within GNAS or STX16, which are associated with loss-of-methylation (LOM) at exon A/B alone or at all maternally methylated GNAS exons. LOM at exon A/B and the resulting biallelic expression of A/B transcripts reduces Gsα expression, thus leading to hormonal resistance. Epigenetic changes at all differentially methylated GNAS regions are also observed in sporadic PHP1B, the most frequent disease variant, which remains unresolved at the molecular level, except for rare cases with paternal uniparental isodisomy or heterodisomy of chromosome 20q (patUPD20q).
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Affiliation(s)
- O Tafaj
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Thier 10, 50 Blossom Street, Boston, MA, 02114, USA
| | - H Jüppner
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Thier 10, 50 Blossom Street, Boston, MA, 02114, USA.
- Pediatric Nephrology Unit, Department of Pediatrics, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
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Grigelioniene G, Nevalainen PI, Reyes M, Thiele S, Tafaj O, Molinaro A, Takatani R, Ala-Houhala M, Nilsson D, Eisfeldt J, Lindstrand A, Kottler ML, Mäkitie O, Jüppner H. A Large Inversion Involving GNAS Exon A/B and All Exons Encoding Gsα Is Associated With Autosomal Dominant Pseudohypoparathyroidism Type Ib (PHP1B). J Bone Miner Res 2017; 32:776-783. [PMID: 28084650 PMCID: PMC5395346 DOI: 10.1002/jbmr.3083] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 12/31/2016] [Accepted: 01/11/2017] [Indexed: 01/08/2023]
Abstract
Pseudohypoparathyroidism type Ib (PHP1B) is characterized primarily by resistance to parathyroid hormone (PTH) and thus hypocalcemia and hyperphosphatemia, in most cases without evidence for Albright hereditary osteodystrophy (AHO). PHP1B is associated with epigenetic changes at one or several differentially-methylated regions (DMRs) within GNAS, which encodes the α-subunit of the stimulatory G protein (Gsα) and splice variants thereof. Heterozygous, maternally inherited STX16 or GNAS deletions leading to isolated loss-of-methylation (LOM) at exon A/B alone or at all maternal DMRs are the cause of autosomal dominant PHP1B (AD-PHP1B). In this study, we analyzed three affected individuals, the female proband and her two sons. All three revealed isolated LOM at GNAS exon A/B, whereas the proband's healthy maternal grandmother and uncle showed normal methylation at this locus. Haplotype analysis was consistent with linkage to the STX16/GNAS region, yet no deletion could be identified. Whole-genome sequencing of one of the patients revealed a large heterozygous inversion (1,882,433 bp). The centromeric breakpoint of the inversion is located 7,225 bp downstream of GNAS exon XL, but its DMR showed no methylation abnormality, raising the possibility that the inversion disrupts a regulatory element required only for establishing or maintaining exon A/B methylation. Because our three patients presented phenotypes consistent with PHP1B, and not with PHP1A, the Gsα promoter is probably unaffected by the inversion. Our findings expand the spectrum of genetic mutations that lead to LOM at exon A/B alone and thus biallelic expression of the transcript derived from this alternative first GNAS exon. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Giedre Grigelioniene
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital Stockholm, Stockholm, Sweden
| | - Pasi I Nevalainen
- Endocrine Unit, Department of Internal Medicine, Tampere University Hospital, Tampere, Finland
| | - Monica Reyes
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Susanne Thiele
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Olta Tafaj
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Angelo Molinaro
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Rieko Takatani
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Marja Ala-Houhala
- Department of Pediatrics, Tampere University Hospital, Tampere, Finland
| | - Daniel Nilsson
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital Stockholm, Stockholm, Sweden
- Science for Life Laboratory, Karolinska Institutet Science Park, Solna, Sweden
| | - Jesper Eisfeldt
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
- Science for Life Laboratory, Karolinska Institutet Science Park, Solna, Sweden
| | - Anna Lindstrand
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital Stockholm, Stockholm, Sweden
| | - Marie-Laure Kottler
- Centre Hospitalier Universitaire de Caen, Department of Genetics, Reference Centre for Rare Disorders of Calcium and Phosphorus Metabolism, Caen, France
| | - Outi Mäkitie
- Children's Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
- Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Harald Jüppner
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Pediatric Nephrology Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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18
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Elli FM, Linglart A, Garin I, de Sanctis L, Bordogna P, Grybek V, Pereda A, Giachero F, Verrua E, Hanna P, Mantovani G, Perez de Nanclares G. The Prevalence of GNAS Deficiency-Related Diseases in a Large Cohort of Patients Characterized by the EuroPHP Network. J Clin Endocrinol Metab 2016; 101:3657-3668. [PMID: 27428667 DOI: 10.1210/jc.2015-4310] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
CONTEXT The term pseudohypoparathyroidism (PHP) was coined to describe the clinical condition resulting from end-organ resistance to parathormone (rPTH), caused by genetic and/or epigenetic alterations within or upstream of GNAS. Although knowledge about PHP is growing, there are few data on the prevalence of underlying molecular defects. OBJECTIVE The purpose of our study was to ascertain the relative prevalence of PHP-associated molecular defects. DESIGN With a specially designed questionnaire, we collected data from all patients (n = 407) clinically and molecularly characterized to date by expert referral centers in France, Italy, and Spain. RESULTS Isolated rPTH (126/407, 31%) was caused only by epigenetic defects, 70% of patients showing loss of imprinting affecting all four GNAS differentially methylated regions and 30% loss of methylation restricted to the GNAS A/B:TSS-DMR. Multihormone resistance with no Albright's hereditary osteodystrophy (AHO) signs (61/407, 15%) was essentially due to epigenetic defects, although 10% of patients had point mutations. In patients with rPTH and AHO (40/407, 10%), the rate of point mutations was higher (28%) and methylation defects lower (about 70%). In patients with multihormone resistance and AHO (155/407, 38%), all types of molecular defects appeared with different frequencies. Finally, isolated AHO (18/407, 4%) and progressive osseous heteroplasia (7/407, 2%) were exclusively caused by point mutations. CONCLUSION With European data, we have established the prevalence of various genetic and epigenetic lesions in PHP-affected patients. Using these findings, we will develop objective criteria to guide cost-effective strategies for genetic testing and explore the implications for management and prognosis.
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Affiliation(s)
- Francesca Marta Elli
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.E., E.V., P.B., G.M.), Department of Clinical Sciences and Community Health, University of Milan, Endocrinology and Diabetology Unit, Milan, Italy; APHP (A.L., V.G., P.H.), Reference Center for Rare Disorders of the Mineral Metabolism and Plateforme d'expertise Paris Sud Maladies Rares, Le Kremlin Bicêtre, France; INSERM U1169 (A.L., V.G., P.H.), Hôpital Bicêtre, Le Kremlin Bicêtre, et Université Paris-Saclay, France; Molecular (Epi)Genetics Laboratory (I.G., A.P., G.P.d.N.), BioAraba National Health Institute, Hospital Universitario Araba-Txagorritxu, Vitoria-Gasteiz, Spain; Department of Public Health and Pediatrics (L.d.S., F.G.), University of Turin, Regina Margherita Children's Hospital, Health and Science City, Turin, Italy; Department of Biochemistry and Molecular Biology (A.P.), University of Basque Country, Leioa, Spain
| | - Agnès Linglart
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.E., E.V., P.B., G.M.), Department of Clinical Sciences and Community Health, University of Milan, Endocrinology and Diabetology Unit, Milan, Italy; APHP (A.L., V.G., P.H.), Reference Center for Rare Disorders of the Mineral Metabolism and Plateforme d'expertise Paris Sud Maladies Rares, Le Kremlin Bicêtre, France; INSERM U1169 (A.L., V.G., P.H.), Hôpital Bicêtre, Le Kremlin Bicêtre, et Université Paris-Saclay, France; Molecular (Epi)Genetics Laboratory (I.G., A.P., G.P.d.N.), BioAraba National Health Institute, Hospital Universitario Araba-Txagorritxu, Vitoria-Gasteiz, Spain; Department of Public Health and Pediatrics (L.d.S., F.G.), University of Turin, Regina Margherita Children's Hospital, Health and Science City, Turin, Italy; Department of Biochemistry and Molecular Biology (A.P.), University of Basque Country, Leioa, Spain
| | - Intza Garin
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.E., E.V., P.B., G.M.), Department of Clinical Sciences and Community Health, University of Milan, Endocrinology and Diabetology Unit, Milan, Italy; APHP (A.L., V.G., P.H.), Reference Center for Rare Disorders of the Mineral Metabolism and Plateforme d'expertise Paris Sud Maladies Rares, Le Kremlin Bicêtre, France; INSERM U1169 (A.L., V.G., P.H.), Hôpital Bicêtre, Le Kremlin Bicêtre, et Université Paris-Saclay, France; Molecular (Epi)Genetics Laboratory (I.G., A.P., G.P.d.N.), BioAraba National Health Institute, Hospital Universitario Araba-Txagorritxu, Vitoria-Gasteiz, Spain; Department of Public Health and Pediatrics (L.d.S., F.G.), University of Turin, Regina Margherita Children's Hospital, Health and Science City, Turin, Italy; Department of Biochemistry and Molecular Biology (A.P.), University of Basque Country, Leioa, Spain
| | - Luisa de Sanctis
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.E., E.V., P.B., G.M.), Department of Clinical Sciences and Community Health, University of Milan, Endocrinology and Diabetology Unit, Milan, Italy; APHP (A.L., V.G., P.H.), Reference Center for Rare Disorders of the Mineral Metabolism and Plateforme d'expertise Paris Sud Maladies Rares, Le Kremlin Bicêtre, France; INSERM U1169 (A.L., V.G., P.H.), Hôpital Bicêtre, Le Kremlin Bicêtre, et Université Paris-Saclay, France; Molecular (Epi)Genetics Laboratory (I.G., A.P., G.P.d.N.), BioAraba National Health Institute, Hospital Universitario Araba-Txagorritxu, Vitoria-Gasteiz, Spain; Department of Public Health and Pediatrics (L.d.S., F.G.), University of Turin, Regina Margherita Children's Hospital, Health and Science City, Turin, Italy; Department of Biochemistry and Molecular Biology (A.P.), University of Basque Country, Leioa, Spain
| | - Paolo Bordogna
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.E., E.V., P.B., G.M.), Department of Clinical Sciences and Community Health, University of Milan, Endocrinology and Diabetology Unit, Milan, Italy; APHP (A.L., V.G., P.H.), Reference Center for Rare Disorders of the Mineral Metabolism and Plateforme d'expertise Paris Sud Maladies Rares, Le Kremlin Bicêtre, France; INSERM U1169 (A.L., V.G., P.H.), Hôpital Bicêtre, Le Kremlin Bicêtre, et Université Paris-Saclay, France; Molecular (Epi)Genetics Laboratory (I.G., A.P., G.P.d.N.), BioAraba National Health Institute, Hospital Universitario Araba-Txagorritxu, Vitoria-Gasteiz, Spain; Department of Public Health and Pediatrics (L.d.S., F.G.), University of Turin, Regina Margherita Children's Hospital, Health and Science City, Turin, Italy; Department of Biochemistry and Molecular Biology (A.P.), University of Basque Country, Leioa, Spain
| | - Virginie Grybek
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.E., E.V., P.B., G.M.), Department of Clinical Sciences and Community Health, University of Milan, Endocrinology and Diabetology Unit, Milan, Italy; APHP (A.L., V.G., P.H.), Reference Center for Rare Disorders of the Mineral Metabolism and Plateforme d'expertise Paris Sud Maladies Rares, Le Kremlin Bicêtre, France; INSERM U1169 (A.L., V.G., P.H.), Hôpital Bicêtre, Le Kremlin Bicêtre, et Université Paris-Saclay, France; Molecular (Epi)Genetics Laboratory (I.G., A.P., G.P.d.N.), BioAraba National Health Institute, Hospital Universitario Araba-Txagorritxu, Vitoria-Gasteiz, Spain; Department of Public Health and Pediatrics (L.d.S., F.G.), University of Turin, Regina Margherita Children's Hospital, Health and Science City, Turin, Italy; Department of Biochemistry and Molecular Biology (A.P.), University of Basque Country, Leioa, Spain
| | - Arrate Pereda
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.E., E.V., P.B., G.M.), Department of Clinical Sciences and Community Health, University of Milan, Endocrinology and Diabetology Unit, Milan, Italy; APHP (A.L., V.G., P.H.), Reference Center for Rare Disorders of the Mineral Metabolism and Plateforme d'expertise Paris Sud Maladies Rares, Le Kremlin Bicêtre, France; INSERM U1169 (A.L., V.G., P.H.), Hôpital Bicêtre, Le Kremlin Bicêtre, et Université Paris-Saclay, France; Molecular (Epi)Genetics Laboratory (I.G., A.P., G.P.d.N.), BioAraba National Health Institute, Hospital Universitario Araba-Txagorritxu, Vitoria-Gasteiz, Spain; Department of Public Health and Pediatrics (L.d.S., F.G.), University of Turin, Regina Margherita Children's Hospital, Health and Science City, Turin, Italy; Department of Biochemistry and Molecular Biology (A.P.), University of Basque Country, Leioa, Spain
| | - Federica Giachero
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.E., E.V., P.B., G.M.), Department of Clinical Sciences and Community Health, University of Milan, Endocrinology and Diabetology Unit, Milan, Italy; APHP (A.L., V.G., P.H.), Reference Center for Rare Disorders of the Mineral Metabolism and Plateforme d'expertise Paris Sud Maladies Rares, Le Kremlin Bicêtre, France; INSERM U1169 (A.L., V.G., P.H.), Hôpital Bicêtre, Le Kremlin Bicêtre, et Université Paris-Saclay, France; Molecular (Epi)Genetics Laboratory (I.G., A.P., G.P.d.N.), BioAraba National Health Institute, Hospital Universitario Araba-Txagorritxu, Vitoria-Gasteiz, Spain; Department of Public Health and Pediatrics (L.d.S., F.G.), University of Turin, Regina Margherita Children's Hospital, Health and Science City, Turin, Italy; Department of Biochemistry and Molecular Biology (A.P.), University of Basque Country, Leioa, Spain
| | - Elisa Verrua
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.E., E.V., P.B., G.M.), Department of Clinical Sciences and Community Health, University of Milan, Endocrinology and Diabetology Unit, Milan, Italy; APHP (A.L., V.G., P.H.), Reference Center for Rare Disorders of the Mineral Metabolism and Plateforme d'expertise Paris Sud Maladies Rares, Le Kremlin Bicêtre, France; INSERM U1169 (A.L., V.G., P.H.), Hôpital Bicêtre, Le Kremlin Bicêtre, et Université Paris-Saclay, France; Molecular (Epi)Genetics Laboratory (I.G., A.P., G.P.d.N.), BioAraba National Health Institute, Hospital Universitario Araba-Txagorritxu, Vitoria-Gasteiz, Spain; Department of Public Health and Pediatrics (L.d.S., F.G.), University of Turin, Regina Margherita Children's Hospital, Health and Science City, Turin, Italy; Department of Biochemistry and Molecular Biology (A.P.), University of Basque Country, Leioa, Spain
| | - Patrick Hanna
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.E., E.V., P.B., G.M.), Department of Clinical Sciences and Community Health, University of Milan, Endocrinology and Diabetology Unit, Milan, Italy; APHP (A.L., V.G., P.H.), Reference Center for Rare Disorders of the Mineral Metabolism and Plateforme d'expertise Paris Sud Maladies Rares, Le Kremlin Bicêtre, France; INSERM U1169 (A.L., V.G., P.H.), Hôpital Bicêtre, Le Kremlin Bicêtre, et Université Paris-Saclay, France; Molecular (Epi)Genetics Laboratory (I.G., A.P., G.P.d.N.), BioAraba National Health Institute, Hospital Universitario Araba-Txagorritxu, Vitoria-Gasteiz, Spain; Department of Public Health and Pediatrics (L.d.S., F.G.), University of Turin, Regina Margherita Children's Hospital, Health and Science City, Turin, Italy; Department of Biochemistry and Molecular Biology (A.P.), University of Basque Country, Leioa, Spain
| | - Giovanna Mantovani
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.E., E.V., P.B., G.M.), Department of Clinical Sciences and Community Health, University of Milan, Endocrinology and Diabetology Unit, Milan, Italy; APHP (A.L., V.G., P.H.), Reference Center for Rare Disorders of the Mineral Metabolism and Plateforme d'expertise Paris Sud Maladies Rares, Le Kremlin Bicêtre, France; INSERM U1169 (A.L., V.G., P.H.), Hôpital Bicêtre, Le Kremlin Bicêtre, et Université Paris-Saclay, France; Molecular (Epi)Genetics Laboratory (I.G., A.P., G.P.d.N.), BioAraba National Health Institute, Hospital Universitario Araba-Txagorritxu, Vitoria-Gasteiz, Spain; Department of Public Health and Pediatrics (L.d.S., F.G.), University of Turin, Regina Margherita Children's Hospital, Health and Science City, Turin, Italy; Department of Biochemistry and Molecular Biology (A.P.), University of Basque Country, Leioa, Spain
| | - Guiomar Perez de Nanclares
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (F.M.E., E.V., P.B., G.M.), Department of Clinical Sciences and Community Health, University of Milan, Endocrinology and Diabetology Unit, Milan, Italy; APHP (A.L., V.G., P.H.), Reference Center for Rare Disorders of the Mineral Metabolism and Plateforme d'expertise Paris Sud Maladies Rares, Le Kremlin Bicêtre, France; INSERM U1169 (A.L., V.G., P.H.), Hôpital Bicêtre, Le Kremlin Bicêtre, et Université Paris-Saclay, France; Molecular (Epi)Genetics Laboratory (I.G., A.P., G.P.d.N.), BioAraba National Health Institute, Hospital Universitario Araba-Txagorritxu, Vitoria-Gasteiz, Spain; Department of Public Health and Pediatrics (L.d.S., F.G.), University of Turin, Regina Margherita Children's Hospital, Health and Science City, Turin, Italy; Department of Biochemistry and Molecular Biology (A.P.), University of Basque Country, Leioa, Spain
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19
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Sanchez-Delgado M, Riccio A, Eggermann T, Maher ER, Lapunzina P, Mackay D, Monk D. Causes and Consequences of Multi-Locus Imprinting Disturbances in Humans. Trends Genet 2016; 32:444-455. [PMID: 27235113 DOI: 10.1016/j.tig.2016.05.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 05/03/2016] [Accepted: 05/04/2016] [Indexed: 12/20/2022]
Abstract
Eight syndromes are associated with the loss of methylation at specific imprinted loci. There has been increasing evidence that these methylation defects in patients are not isolated events occurring at a given disease-associated locus but that some of these patients may have multi-locus imprinting disturbances (MLID) affecting additional imprinted regions. With the recent advances in technology, methylation profiling has revealed that imprinted loci represent only a small fraction of the methylation differences observed between the gametes. To figure out how imprinting anomalies occur at multiple imprinted domains, we have to understand the interplay between DNA methylation and histone modifications in the process of selective imprint protection during pre-implantation reprogramming, which, if disrupted, leads to these complex imprinting disorders (IDs).
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Affiliation(s)
- Marta Sanchez-Delgado
- Imprinting and Cancer group, Cancer Epigenetic and Biology Program, Institut d'Investigació Biomedica de Bellvitge, Hospital Duran i Reynals, Barcelona, Spain
| | - Andrea Riccio
- DiSTABiF, Seconda Università degli Studi di Napoli, Caserta; Institute of Genetics and Biophysics - ABT, CNR, Napoli, Italy
| | - Thomas Eggermann
- Institute of Human Genetics University Hospital Aachen, Aachen, Germany
| | - Eamonn R Maher
- Department of Medical Genetics, University of Cambridge and NIHR Cambridge Biomedical Research Centre, Cambridge, UK
| | - Pablo Lapunzina
- Instituto de Genética Médica y Molecular (INGEMM)-IdiPAZ, Hospital Universitario La Paz, Madrid, Spain; CIBERER, Centro deInvestigación Biomédica en Red de Enfermedades Raras, ISCIII, Madrid, Spain
| | - Deborah Mackay
- Human Genetics and Genomic Medicine, Faculty of Medicine University of Southampton, Southampton, UK
| | - David Monk
- Imprinting and Cancer group, Cancer Epigenetic and Biology Program, Institut d'Investigació Biomedica de Bellvitge, Hospital Duran i Reynals, Barcelona, Spain.
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20
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Takatani R, Molinaro A, Grigelioniene G, Tafaj O, Watanabe T, Reyes M, Sharma A, Singhal V, Raymond FL, Linglart A, Jüppner H. Analysis of Multiple Families With Single Individuals Affected by Pseudohypoparathyroidism Type Ib (PHP1B) Reveals Only One Novel Maternally Inherited GNAS Deletion. J Bone Miner Res 2016; 31:796-805. [PMID: 26479409 PMCID: PMC4826817 DOI: 10.1002/jbmr.2731] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 10/05/2015] [Accepted: 10/12/2015] [Indexed: 01/22/2023]
Abstract
Proximal tubular resistance to parathyroid hormone (PTH) resulting in hypocalcemia and hyperphosphatemia are preeminent abnormalities in pseudohypoparathyroidism type Ib (PHP1B), but resistance toward other hormones as well as variable features of Albright's Hereditary Osteodystrophy (AHO) can occur also. Genomic DNA from PHP1B patients shows epigenetic changes at one or multiple differentially methylated regions (DMRs) within GNAS, the gene encoding Gαs and splice variants thereof. In the autosomal dominant disease variant, these methylation abnormalities are caused by deletions in STX16 or GNAS on the maternal allele. The molecular defect(s) leading to sporadic PHP1B (sporPHP1B) remains in most cases unknown and we therefore analyzed 60 sporPHP1B patients and available family members by microsatellite markers, single nucleotide polymorphisms (SNPs), multiplex ligation-dependent probe amplification (MLPA), and methylation-specific MLPA (MS-MLPA). All investigated cases revealed broad GNAS methylation changes, but no evidence for inheritance of two paternal chromosome 20q alleles. Some patients with partial epigenetic modifications in DNA from peripheral blood cells showed more complete GNAS methylation changes when testing their immortalized lymphoblastoid cells. Analysis of siblings and children of sporPHP1B patients provided no evidence for an abnormal mineral ion regulation and no changes in GNAS methylation. Only one patient revealed, based on MLPA and microsatellite analyses, evidence for an allelic loss, which resulted in the discovery of two adjacent, maternally inherited deletions (37,597 and 1427 bp, respectively) that remove the area between GNAS antisense exons 3 and 5, including exon NESP. Our findings thus emphasize that the region comprising antisense exons 3 and 4 is required for establishing all maternal GNAS methylation imprints. The genetic defect(s) leading in sporPHP1B to epigenetic GNAS changes and thus PTH-resistance remains unknown, but it seems unlikely that this disease variant is caused by heterozygous inherited or de novo mutations involving GNAS.
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Affiliation(s)
- Rieko Takatani
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Angelo Molinaro
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Giedre Grigelioniene
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Olta Tafaj
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Tomoyuki Watanabe
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Monica Reyes
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Amita Sharma
- Pediatric Nephrology Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Vibha Singhal
- Pediatric Endocrinology Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - F Lucy Raymond
- Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Agnès Linglart
- Paediatric Endocrinology and Diabetology, French National Reference Centre for Rare Disorders of Mineral Metabolism, AP-HP Hôpital Bicêtre Paris Sud, le Kremlin-Bicêtre, France
- Faculté de Médecine, Université Paris Sud, le Kremlin-Bicêtre, France
| | - Harald Jüppner
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Pediatric Nephrology Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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21
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Rochtus A, Martin-Trujillo A, Izzi B, Elli F, Garin I, Linglart A, Mantovani G, Perez de Nanclares G, Thiele S, Decallonne B, Van Geet C, Monk D, Freson K. Genome-wide DNA methylation analysis of pseudohypoparathyroidism patients with GNAS imprinting defects. Clin Epigenetics 2016; 8:10. [PMID: 26819647 PMCID: PMC4728790 DOI: 10.1186/s13148-016-0175-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 01/17/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Pseudohypoparathyroidism (PHP) is caused by (epi)genetic defects in the imprinted GNAS cluster. Current classification of PHP patients is hampered by clinical and molecular diagnostic overlaps. The European Consortium for the study of PHP designed a genome-wide methylation study to improve molecular diagnosis. METHODS The HumanMethylation 450K BeadChip was used to analyze genome-wide methylation in 24 PHP patients with parathyroid hormone resistance and 20 age- and gender-matched controls. Patients were previously diagnosed with GNAS-specific differentially methylated regions (DMRs) and include 6 patients with known STX16 deletion (PHP(Δstx16)) and 18 without deletion (PHP(neg)). RESULTS The array demonstrated that PHP patients do not show DNA methylation differences at the whole-genome level. Unsupervised clustering of GNAS-specific DMRs divides PHP(Δstx16) versus PHP(neg) patients. Interestingly, in contrast to the notion that all PHP patients share methylation defects in the A/B DMR while only PHP(Δstx16) patients have normal NESP, GNAS-AS1 and XL methylation, we found a novel DMR (named GNAS-AS2) in the GNAS-AS1 region that is significantly different in both PHP(Δstx16) and PHP(neg), as validated by Sequenom EpiTYPER in a larger PHP cohort. The analysis of 58 DMRs revealed that 8/18 PHP(neg) and 1/6 PHP(Δstx16) patients have multi-locus methylation defects. Validation was performed for FANCC and SVOPL DMRs. CONCLUSIONS This is the first genome-wide methylation study for PHP patients that confirmed that GNAS is the most significant DMR, and the presence of STX16 deletion divides PHP patients in two groups. Moreover, a novel GNAS-AS2 DMR affects all PHP patients, and PHP patients seem sensitive to multi-locus methylation defects.
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Affiliation(s)
- Anne Rochtus
- Department of Cardiovascular Sciences, Center for Molecular and Vascular Biology, University of Leuven, Campus Gasthuisberg, O&N1, Herestraat 49, Box 911, 3000 Leuven, Belgium ; Department of Pediatrics, University Hospitals Leuven, 3000 Leuven, Belgium
| | | | - Benedetta Izzi
- Department of Cardiovascular Sciences, Center for Molecular and Vascular Biology, University of Leuven, Campus Gasthuisberg, O&N1, Herestraat 49, Box 911, 3000 Leuven, Belgium
| | - Francesca Elli
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Endocrinology and Diabetology Unit, Department of Clinical Sciences and Community Health, University of Milan, 20122, Milan, Italy
| | - Intza Garin
- Molecular (Epi)Genetics Laboratory, BioAraba National Health Institute, Hospital Universitario Araba-Txagorritxu, 01009 Vitoria-Gasteiz, Spain
| | - Agnes Linglart
- Department of Pediatric Endocrinology and Diabetology for Children, APHP, Bicêtre Paris Sud, 94275 Le Kremlin Bicêtre, France ; Reference Center for Rare Disorders of the Mineral Metabolism and Plateforme d'Expertise Paris Sud, APHP, 94275 Le Kremlin Bicêtre, France
| | - Giovanna Mantovani
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Endocrinology and Diabetology Unit, Department of Clinical Sciences and Community Health, University of Milan, 20122, Milan, Italy
| | - Guiomar Perez de Nanclares
- Molecular (Epi)Genetics Laboratory, BioAraba National Health Institute, Hospital Universitario Araba-Txagorritxu, 01009 Vitoria-Gasteiz, Spain
| | - Suzanne Thiele
- Division of Experimental Paediatric Endocrinology and Diabetes, Department of Paediatrics, University of Luebeck, 23560 Luebeck, Germany
| | - Brigitte Decallonne
- Department of Clinical and Experimental Endocrinology, University of Leuven, 3000 Leuven, Belgium
| | - Chris Van Geet
- Department of Pediatrics, University Hospitals Leuven, 3000 Leuven, Belgium
| | - David Monk
- Laboratory of Genomic Imprinting and Cancer, IDIBELL, 08908 Barcelona, Spain
| | - Kathleen Freson
- Department of Cardiovascular Sciences, Center for Molecular and Vascular Biology, University of Leuven, Campus Gasthuisberg, O&N1, Herestraat 49, Box 911, 3000 Leuven, Belgium
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22
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Takatani R, Minagawa M, Molinaro A, Reyes M, Kinoshita K, Takatani T, Kazukawa I, Nagatsuma M, Kashimada K, Sato K, Matsushita K, Nomura F, Shimojo N, Jüppner H. Similar frequency of paternal uniparental disomy involving chromosome 20q (patUPD20q) in Japanese and Caucasian patients affected by sporadic pseudohypoparathyroidism type Ib (sporPHP1B). Bone 2015; 79:15-20. [PMID: 25997889 PMCID: PMC4501871 DOI: 10.1016/j.bone.2015.05.011] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 04/24/2015] [Accepted: 05/08/2015] [Indexed: 02/08/2023]
Abstract
Pseudohypoparathyroidism type Ib (PHP1B) is caused by proximal tubular resistance to parathyroid hormone that occurs in most cases in the absence of Albright's Hereditary Osteodystrophy (AHO). Familial forms of PHP1B are caused by maternally inherited microdeletions within STX16, the gene encoding syntaxin 16, or within GNAS, a complex genetic locus on chromosome 20q13.3 encoding Gsα and several splice variants thereof. These deletions lead either to a loss-of-methylation affecting GNAS exon A/B alone or to epigenetic changes involving multiple differentially methylated regions (DMRs) within GNAS. Broad GNAS methylation abnormalities are also observed in most sporadic PHP1B (sporPHP1B) cases. However, with the exception of paternal uniparental disomy involving chromosome 20q (patUPD20q), the molecular mechanism leading to this disease variant remains unknown. We now investigated 23 Japanese sporPHP1B cases, who presented with hypocalcemia, hyperphosphatemia, elevated PTH levels, and occasionally with TSH elevations and mild AHO features. Age at diagnosis was 10.6 ± 1.45 years. Calcium, phosphate, and PTH were 6.3 ± 0.23 mg/dL, 7.7 ± 0.33 mg/dL, and 305 ± 34.5 pg/mL, respectively, i.e. laboratory findings that are indistinguishable from those previously observed for Caucasian sporPHP1B cases. All investigated patients showed broad GNAS methylation changes. Eleven individuals were homozygous for SNPs within exon NESP and a pentanucleotide repeat in exon A/B. Two of these patients furthermore revealed homozygosity for numerous microsatellite markers on chromosome 20q raising the possibility of patUPD20q, which was confirmed through the analysis of parental DNA. Based on this and our previous reports, paternal duplication of the chromosomal region comprising the GNAS locus appears to be a fairly common cause of sporPHP1B that is likely to occur with equal frequency in Caucasians and Asians.
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Affiliation(s)
- Rieko Takatani
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA; Department of Pediatrics, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Masanori Minagawa
- Department of Pediatrics, Graduate School of Medicine, Chiba University, Chiba, Japan; Department of Endocrinology, Chiba Children's Hospital, Chiba, Japan
| | - Angelo Molinaro
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA; Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Pisa, University Hospital of Pisa, Pisa, Italy
| | - Monica Reyes
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Kaori Kinoshita
- Department of Pediatrics, Kimitsu Chuo Hospital, Kisarazu, Japan
| | - Tomozumi Takatani
- Department of Pediatrics, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Itsuro Kazukawa
- Department of Pediatrics, Graduate School of Medicine, Chiba University, Chiba, Japan; Department of Endocrinology, Chiba Children's Hospital, Chiba, Japan
| | - Misako Nagatsuma
- Department of Pediatrics and Developmental Biology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kenichi Kashimada
- Department of Pediatrics and Developmental Biology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kenichi Sato
- Department of Medical Technology and Sciences, International University of Health and Welfare, Fukuoka, Japan
| | - Kazuyuki Matsushita
- Department of Molecular Diagnosis & Division of Clinical Genetics and Proteomics, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Fumio Nomura
- Department of Molecular Diagnosis & Division of Clinical Genetics and Proteomics, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Naoki Shimojo
- Department of Pediatrics, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Harald Jüppner
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
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23
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Abstract
The GNAS complex locus encodes the alpha-subunit of the stimulatory G protein (Gsα), a ubiquitous signaling protein mediating the actions of many hormones, neurotransmitters, and paracrine/autocrine factors via generation of the second messenger cAMP. GNAS gives rise to other gene products, most of which exhibit exclusively monoallelic expression. In contrast, Gsα is expressed biallelically in most tissues; however, paternal Gsα expression is silenced in a small number of tissues through as-yet-poorly understood mechanisms that involve differential methylation within GNAS. Gsα-coding GNAS mutations that lead to diminished Gsα expression and/or function result in Albright's hereditary osteodystrophy (AHO) with or without hormone resistance, i.e., pseudohypoparathyroidism type-Ia/Ic and pseudo-pseudohypoparathyroidism, respectively. Microdeletions that alter GNAS methylation and, thereby, diminish Gsα expression in tissues in which the paternal Gsα allele is normally silenced also cause hormone resistance, which occurs typically in the absence of AHO, a disorder termed pseudohypoparathyroidism type-Ib. Mutations of GNAS that cause constitutive Gsα signaling are found in patients with McCune-Albright syndrome, fibrous dysplasia of bone, and different endocrine and non-endocrine tumors. Clinical features of these diseases depend significantly on the parental allelic origin of the GNAS mutation, reflecting the tissue-specific paternal Gsα silencing. In this article, we review the pathogenesis and the phenotypes of these human diseases.
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Affiliation(s)
- Serap Turan
- Pediatric Endocrinology, Marmara University School of Medicine Hospital, Istanbul, Turkey;
| | - Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114;
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24
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Molinaro A, Tiosano D, Takatani R, Chrysis D, Russell W, Koscielniak N, Kottler ML, Agretti P, De Marco G, Ahtiainen P, Christov M, Mäkitie O, Tonacchera M, Jüppner H. TSH elevations as the first laboratory evidence for pseudohypoparathyroidism type Ib (PHP-Ib). J Bone Miner Res 2015; 30:906-12. [PMID: 25403028 PMCID: PMC4401615 DOI: 10.1002/jbmr.2408] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 11/05/2014] [Accepted: 11/10/2014] [Indexed: 01/21/2023]
Abstract
Hypocalcemia and hyperphosphatemia because of resistance toward parathyroid hormone (PTH) in the proximal renal tubules are the most prominent abnormalities in patients affected by pseudohypoparathyroidism type Ib (PHP-Ib). In this rare disorder, which is caused by GNAS methylation changes, resistance can occur toward other hormones, such as thyroid-stimulating hormone (TSH), that mediate their actions through G protein-coupled receptors. However, these additional laboratory abnormalities are usually not recognized until PTH-resistant hypocalcemia becomes clinically apparent. We now describe four pediatric patients, first diagnosed with subclinical or overt hypothyroidism between the ages of 0.2 and 15 years, who developed overt PTH-resistance 3 to 20 years later. Although anti-thyroperoxidase (anti-TPO) antibodies provided a plausible explanation for hypothyroidism in one of these patients, this and two other patients revealed broad epigenetic GNAS abnormalities, which included loss of methylation (LOM) at exons AS, XL, and A/B, and gain of methylation at exon NESP55; ie, findings consistent with PHP-Ib. LOM at GNAS exon A/B alone led in the fourth patient to the identification of a maternally inherited 3-kb STX16 deletion, a well-established cause of autosomal dominant PHP-Ib. Although GNAS methylation changes were not detected in additional pediatric and adult patients with subclinical hypothyroidism (23 pediatric and 39 adult cases), hypothyroidism can obviously be the initial finding in PHP-Ib patients. One should therefore consider measuring PTH, along with calcium and phosphate, in patients with unexplained hypothyroidism for extended periods of time to avoid hypocalcemia and associated clinical complications.
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Affiliation(s)
- Angelo Molinaro
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Pisa, University Hospital of Pisa, Pisa, Italy
| | - Dov Tiosano
- Division of Pediatric Endocrinology, Meyer Children's Hospital, Rambam Health Care Campus, Haifa, Israel
| | - Rieko Takatani
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Dionisios Chrysis
- Department of Pediatrics, Medical School, University of Patras, Patras, Greece
| | - William Russell
- Division of Pediatric Endocrinology and Diabetes, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Nikolas Koscielniak
- Program in Occupational Therapy, Washington University School of Medicine, St. Louis, MO, USA
| | - Marie-Laure Kottler
- Centre Hospitalier Universitaire de Caen, Department of Genetics, Reference Centre for Rare Disorders of Calcium and Phosphorus Metabolism, F-14000 Caen, France
| | - Patrizia Agretti
- Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Pisa, University Hospital of Pisa, Pisa, Italy
| | - Giuseppina De Marco
- Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Pisa, University Hospital of Pisa, Pisa, Italy
| | - Petteri Ahtiainen
- Central Finland Central Hospital, Jyväskylä, and Kuopio University Hospital, Kuopio, Finland
| | - Marta Christov
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Outi Mäkitie
- Hospital for Children and Adolescents, University of Helsinki, and Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Massimo Tonacchera
- Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Pisa, University Hospital of Pisa, Pisa, Italy
| | - Harald Jüppner
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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Jüppner H. Genetic and epigenetic defects at the GNAS locus cause different forms of pseudohypoparathyroidism. ANNALES D'ENDOCRINOLOGIE 2015; 76:92-7. [PMID: 25882888 DOI: 10.1016/j.ando.2015.03.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 03/17/2015] [Indexed: 01/07/2023]
Affiliation(s)
- Harald Jüppner
- Endocrine Unit and Pediatric Nephrology Unit, Massachusetts General Hospital and Harvard Medical School, 02114 Boston, United States.
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European guidance for the molecular diagnosis of pseudohypoparathyroidism not caused by point genetic variants at GNAS: an EQA study. Eur J Hum Genet 2014; 23:438-44. [PMID: 25005735 DOI: 10.1038/ejhg.2014.127] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 05/20/2014] [Accepted: 05/30/2014] [Indexed: 12/19/2022] Open
Abstract
Pseudohypoparathyroidism is a rare endocrine disorder that can be caused by genetic (mainly maternally inherited inactivating point mutations, although intragenic and gross deletions have rarely been reported) or epigenetic alterations at GNAS locus. Clinical and molecular characterization of this disease is not that easy because of phenotypic, biochemical and molecular overlapping features between both subtypes of the disease. The European Consortium for the study of PHP (EuroPHP) designed the present work with the intention of generating the standards of diagnostic clinical molecular (epi)genetic testing in PHP patients. With this aim, DNA samples of eight independent PHP patients carrying GNAS genetic and/or epigenetic defects (three patients with GNAS deletions, two with 20q uniparental disomy and three with a methylation defect of unknown origin) without GNAS point mutations were anonymized and sent to the five participant laboratories for their routine genetic analysis (methylation-specific (MS)-MLPA, pyrosequencing and EpiTYPER) and interpretations. All laboratories were able to detect methylation defects and, after the data analysis, the Consortium compared the results to define technical advantages and disadvantages of different techniques. To conclude, we propose as first-level investigation in PHP patients copy number and methylation analysis by MS-MLPA. Then, in patients with partial methylation defect, the result should be confirmed by single CpG bisulphite-based methods (ie pyrosequencing), whereas in case of a complete methylation defect without detectable deletion, microsatellites or SNP genotyping should be performed to exclude uniparental disomy 20.
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Domínguez García A, Castaño González L, Pérez-Nanclares G, Quinteiro González S, Caballero Fernández E. Aspectos clínicos en dos casos de seudohipoparatiroidismo ( i a y i b) y estudio molecular del locus GNAS. An Pediatr (Barc) 2013; 79:319-24. [DOI: 10.1016/j.anpedi.2013.03.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Revised: 03/08/2013] [Accepted: 03/11/2013] [Indexed: 11/28/2022] Open
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Yuno A, Usui T, Yambe Y, Higashi K, Ugi S, Shinoda J, Mashio Y, Shimatsu A. Genetic and epigenetic states of the GNAS complex in pseudohypoparathyroidism type Ib using methylation-specific multiplex ligation-dependent probe amplification assay. Eur J Endocrinol 2013; 168:169-75. [PMID: 23132697 DOI: 10.1530/eje-12-0548] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
CONTEXT Pseudohypoparathyroidism type Ib (PHP-Ib) is a rare disorder resulting from genetic and epigenetic aberrations in the GNAS complex. PHP-Ib, usually defined by renal resistance to parathyroid hormone, is due to a maternal loss of GNAS exon A/B methylation and leads to decreased expression of the stimulatory G protein α (Gsα) in specific tissues. OBJECTIVE To clarify the usefulness of methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA), we evaluated genetic and epigenetic changes of the GNAS locus in Japanese PHP-Ib patients. DESIGN Retrospective case series. PATIENTS We studied 13 subjects with PHP-Ib (three families with eight affected members and one unaffected member and four sporadic cases). MEASUREMENTS The methylation status of GNAS differentially methylated regions (DMRs) was evaluated using MS-MLPA. The main outcome measure was the presence of deletion mutations in the GNAS locus and STX16, which were assessed using MLPA. RESULTS In all familial PHP-Ib cases, a ~3 kb deletion of STX16 and demethylation of the A/B domain were identified. In contrast, no deletion was detected throughout the entire GNAS locus region in the sporadic cases. Broad methylation abnormalities were observed in the GNAS DMRs. CONCLUSIONS MS-MLPA allows for precise and rapid analysis of the methylation status in GNAS DMRs as well as the detection of microdeletion mutations in PHP-Ib. Results confirm the previous findings in this disorder and demonstrate that this method is valuable for the genetic evaluation and visualizing the methylation status. The MS-MLPA assay is a useful tool that may facilitate making the molecular diagnosis of PHP-Ib.
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Affiliation(s)
- Akiko Yuno
- Clinical Research Institute, National Hospital Organization Kyoto Medical Center, 1-1 Mukaihata-cho, Fukakusa, Fushimi-ku, Kyoto 612-8555, Japan
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Turan S, Bastepe M. The GNAS complex locus and human diseases associated with loss-of-function mutations or epimutations within this imprinted gene. Horm Res Paediatr 2013; 80:229-41. [PMID: 24107509 PMCID: PMC3874326 DOI: 10.1159/000355384] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 08/29/2013] [Indexed: 12/14/2022] Open
Abstract
GNAS is a complex imprinted locus leading to several different gene products that show exclusive monoallelic expression. GNAS also encodes the α-subunit of the stimulatory G protein (Gsα), a ubiquitously expressed signaling protein that is essential for the actions of many hormones and other endogenous molecules. Gsα is expressed biallelically in most tissues but its expression is silenced from the paternal allele in a small number of tissues. The tissue-specific paternal silencing of Gsα results in different parent-of-origin-specific phenotypes in patients who carry inactivating GNAS mutations. In this paper, we review the GNAS complex locus and discuss how disruption of Gsα expression and the expression of other GNAS products shape the phenotypes of human disorders caused by mutations in this gene.
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Affiliation(s)
- Serap Turan
- Pediatric Endocrinology, Marmara University School of Medicine Hospital, Istanbul, Turkey
| | - Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA
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Turan S, Ignatius J, Moilanen JS, Kuismin O, Stewart H, Mann NP, Linglart A, Bastepe M, Jüppner H. De novo STX16 deletions: an infrequent cause of pseudohypoparathyroidism type Ib that should be excluded in sporadic cases. J Clin Endocrinol Metab 2012; 97:E2314-9. [PMID: 23087324 PMCID: PMC3513531 DOI: 10.1210/jc.2012-2920] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Accepted: 09/24/2012] [Indexed: 01/18/2023]
Abstract
CONTEXT Maternally inherited 3-kb STX16 deletions cause autosomal dominant pseudohypoparathyroidism type Ib (PHP-Ib) characterized by PTH resistance with loss of methylation restricted to the GNAS exon A/B. OBJECTIVE The objective of the study was to search for the 3-kb STX16 deletion and to establish haplotypes for the GNAS region for two PHP-Ib patients and their families. SETTING The study was conducted at a research laboratory and tertiary care hospitals. PATIENTS The index cases presented at the ages 8 and 9.5 yr, respectively, with hypocalcemia, hyperphosphatemia, and elevated PTH. INTERVENTIONS There were no interventions. RESULTS DNA analyses of the index cases revealed an isolated loss of the GNAS exon A/B methylation and the 3-kb STX16 deletion. In the first family, the patient's healthy mother and sister showed no genetic or epigenetic abnormality, yet microsatellite analysis of the GNAS region indicated that both siblings share the same maternal allele, with the exception of an allelic loss for marker 261P9-CA1 (located within STX16), leading to the conclusion that a de novo mutation had occurred on the maternal allele. In the second family, three siblings of the index case are also affected, and an analysis of their DNA revealed the 3-kb STX16 deletion, which was also found in the healthy mother and a maternal uncle. Analysis of the siblings of the deceased maternal grandfather and some of their descendants excluded the 3-kb STX16 deletion, but haplotype analysis of the GNAS region suggested that he had acquired the mutation de novo. CONCLUSIONS De novo 3-kb STX16 deletions, reported only once previously, are infrequent but should be excluded in all cases of PHP-Ib, even when the family history is negative for an inherited form of this disorder.
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Affiliation(s)
- Serap Turan
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA
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Izzi B, Francois I, Labarque V, Thys C, Wittevrongel C, Devriendt K, Legius E, Van den Bruel A, D'Hooghe M, Lambrechts D, de Zegher F, Van Geet C, Freson K. Methylation defect in imprinted genes detected in patients with an Albright's hereditary osteodystrophy like phenotype and platelet Gs hypofunction. PLoS One 2012; 7:e38579. [PMID: 22679513 PMCID: PMC3367970 DOI: 10.1371/journal.pone.0038579] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 05/07/2012] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Pseudohypoparathyroidism (PHP) indicates a group of heterogeneous disorders whose common feature is represented by impaired signaling of hormones that activate Gsalpha, encoded by the imprinted GNAS gene. PHP-Ib patients have isolated Parathormone (PTH) resistance and GNAS epigenetic defects while PHP-Ia cases present with hormone resistance and characteristic features jointly termed as Albright's Hereditary Osteodystrophy (AHO) due to maternally inherited GNAS mutations or similar epigenetic defects as found for PHP-Ib. Pseudopseudohypoparathyroidism (PPHP) patients with an AHO phenotype and no hormone resistance and progressive osseous heteroplasia (POH) cases have inactivating paternally inherited GNAS mutations. METHODOLOGY/PRINCIPAL FINDINGS We here describe 17 subjects with an AHO-like phenotype that could be compatible with having PPHP but none of them carried Gsalpha mutations. Functional platelet studies however showed an obvious Gs hypofunction in the 13 patients that were available for testing. Methylation for the three differentially methylated GNAS regions was quantified via the Sequenom EpiTYPER. Patients showed significant hypermethylation of the XL amplicon compared to controls (36 ± 3 vs. 29 ± 3%; p<0.001); a pattern that is reversed to XL hypomethylation found in PHPIb. Interestingly, XL hypermethylation was associated with reduced XLalphaS protein levels in the patients' platelets. Methylation for NESP and ExonA/B was significantly different for some but not all patients, though most patients have site-specific CpG methylation abnormalities in these amplicons. Since some AHO features are present in other imprinting disorders, the methylation of IGF2, H19, SNURF and GRB10 was quantified. Surprisingly, significant IGF2 hypermethylation (20 ± 10 vs. 14 ± 7%; p<0.05) and SNURF hypomethylation (23 ± 6 vs. 32 6%; p<0.001) was found in patients vs. controls, while H19 and GRB10 methylation was normal. CONCLUSION/SIGNIFICANCE In conclusion, this is the first report of methylation defects including GNAS in patients with an AHO-like phenotype without endocrinological abnormalities. Additional studies are still needed to correlate the methylation defect with the clinical phenotype.
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Affiliation(s)
- Benedetta Izzi
- Center for Molecular and Vascular Biology, University of Leuven, Leuven, Belgium
| | - Inge Francois
- Departement of Pediatrics, University of Leuven, Leuven, Belgium
| | - Veerle Labarque
- Departement of Pediatrics, University of Leuven, Leuven, Belgium
| | - Chantal Thys
- Center for Molecular and Vascular Biology, University of Leuven, Leuven, Belgium
| | | | - Koen Devriendt
- Center for Human Genetics, University of Leuven, Leuven, Belgium
| | - Eric Legius
- Center for Human Genetics, University of Leuven, Leuven, Belgium
| | | | | | | | | | - Chris Van Geet
- Center for Molecular and Vascular Biology, University of Leuven, Leuven, Belgium
- Departement of Pediatrics, University of Leuven, Leuven, Belgium
| | - Kathleen Freson
- Center for Molecular and Vascular Biology, University of Leuven, Leuven, Belgium
- * E-mail:
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Perez-Nanclares G, Romanelli V, Mayo S, Garin I, Zazo Seco C, Fernandez-Rebollo E, Martínez F, Lapunzina P, de Nanclares GP. Detection of hypomethylation syndrome among patients with epigenetic alterations at the GNAS locus. J Clin Endocrinol Metab 2012; 97:E1060-7. [PMID: 22492776 DOI: 10.1210/jc.2012-1081] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
CONTEXT Genomic imprinting is the modification of the genome so that genes from only one (rather than two) of the parental alleles are expressed. The mechanism underlying imprinting is epigenetic, occurring via changes in DNA methylation and histone modifications rather than through alterations in the DNA sequence. To date, nine different imprinting disorders have been clinically and genetically identified and a considerable research effort has been focused on determining the cause of the corresponding methylation defects. OBJECTIVE Our objective was to identify multilocus imprinting defects and characterize any mutations in trans-acting genes in patients with pseudohypoparathyroidism (PHP) caused by epigenetic alterations at GNAS locus. DESIGN We have investigated multilocus imprinting defects in 22 PHP patients with aberrant methylation at the GNAS locus not due to previously described deletions or to paternal uniparental disomy (UPD) of chromosome 20. RESULTS We found that, in contrast to what has been described in growth disorders, multilocus hypomethylation is an uncommon event in PHP patients. We were also unable to identify any genetic alteration causative of the epigenetic defects in the currently known methylation regulatory genes. CONCLUSION Our work suggests that a trans-acting gene regulating the establishment or maintenance of imprinting at GNAS locus, if it exists, should be specific to PHP cases caused by epigenetic defects at GNAS.
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Affiliation(s)
- Gustavo Perez-Nanclares
- Molecular (Epi)Genetics Lab Research Unit, Hospital Txagorritxu, E-01009, Vitoria-Gasteiz, Alava, Spain
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Tomizawa SI, Sasaki H. Genomic imprinting and its relevance to congenital disease, infertility, molar pregnancy and induced pluripotent stem cell. J Hum Genet 2012; 57:84-91. [DOI: 10.1038/jhg.2011.151] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Puzhko S, Goodyer CG, Kerachian MA, Canaff L, Misra M, Jüppner H, Bastepe M, Hendy GN. Parathyroid hormone signaling via Gαs is selectively inhibited by an NH(2)-terminally truncated Gαs: implications for pseudohypoparathyroidism. J Bone Miner Res 2011; 26:2473-85. [PMID: 21713996 PMCID: PMC3916968 DOI: 10.1002/jbmr.461] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Pseudohypoparathyroid patients have resistance predominantly to parathyroid hormone (PTH), and here we have examined the ability of an alternative Gαs-related protein to inhibit Gαs activity in a hormone-selective manner. We tested whether the GNAS exon A/B-derived NH(2)-terminally truncated (Tr) αs protein alters stimulation of adenylate cyclase by the PTH receptor (PTHR1), the thyroid-stimulating hormone (TSH) receptor (TSHR), the β(2)-adrenergic receptor (β(2)AR), or the AVP receptor (V2R). HEK293 cells cotransfected with receptor and full-length (FL) Gαs ± Tr αs protein expression vectors were stimulated with agonists (PTH [10(-7) to 10(-9) M], TSH [1 to 100 mU], isoproterenol [10(-6) to 10(-8) M], or AVP [10(-6) to 10(-8) M]). Following PTH stimulation, HEK293 cells cotransfected with PTHR1 + FL Gαs + Tr αs had a significantly lower cAMP response than those transfected with only PTHR1 + FL Gαs. Tr αs also exerted an inhibitory effect on the cAMP levels stimulated by TSH via the TSHR but had little or no effect on isoproterenol or AVP acting via β(2)AR or V2R, respectively. These differences mimic the spectrum of hormone resistance in pseudohypoparathyroidism type 1a (PHP-1a) and type 1b (PHP-1b) patients. In opossum kidney (OK) cells, endogenously expressing the PTHR1 and β(2)AR, the exogenous expression of Tr αs at a level similar to endogenous FL Gαs resulted in blunting of the cAMP response to PTH, whereas that to isoproterenol was unaltered. A pseudopseudohypoparathyroid patient with Albright hereditary osteodystrophy harbored a de novo paternally inherited M1I Gαs mutation. Similar maternally inherited mutations at the initiation codon have been identified previously in PHP-1a patients. The M1I αs mutant (lacking the first 59 amino acids of Gαs) blunted the increase in cAMP levels stimulated via the PTHR1 in both HEK293 and OK cells similar to the Tr αs protein. Thus NH(2)-terminally truncated forms of Gαs may contribute to the pathogenesis of pseudohypoparathyroidism by inhibiting the activity of Gαs itself in a GPCR selective manner.
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Affiliation(s)
- Svetlana Puzhko
- Endocrine Research Laboratory, McGill University, Montreal, Quebec, Canada
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35
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Abstract
Genomic imprinting is an important and enigmatic form of gene regulation in mammals in which one copy of a gene is silenced in a manner determined by its parental history. Imprinted genes range from those with constitutive monoallelic silencing to those, typically more remote from imprinting control regions, that display developmentally regulated, tissue-specific or partial monoallelic expression. This diversity may make these genes, and the processes they control, more or less sensitive to factors that modify or disrupt epigenetic marks. Imprinted genes have important functions in development and physiology, including major endocrine/neuroendocrine axes. Owing to is central role in coordinating growth, metabolism and reproduction, as well as evidence from genetic and knockout studies, the hypothalamus may be a focus for imprinted gene action. Are there unifying principles that explain why a gene should be imprinted? Conflict between parental genomes over limiting maternal resources, but also co-adaptation between mothers and offspring, have been invoked to explain the evolution of imprinting. Recent reports suggest there may be many more genes imprinted in the hypothalamus than hitherto expected, and it will be important for these new candidates to be validated and to determine whether they conform to current notions of how imprinting is regulated. In fully evaluating the role of imprinted genes in the hypothalamus, much work needs to be done to identify the specific neuronal populations in which particular genes are expressed, establish whether there are pathways in common and whether imprinted genes are involved in long-term programming of hypothalamic functions.
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Affiliation(s)
- Elena Ivanova
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, UK
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Abstract
CONTEXT The term pseudohypoparathyroidism (PHP) indicates a group of heterogeneous disorders whose common feature is represented by impaired signaling of various hormones (primarily PTH) that activate cAMP-dependent pathways via Gsα protein. The two main subtypes of PHP, PHP type Ia, and Ib (PHP-Ia, PHP-Ib) are caused by molecular alterations within or upstream of the imprinted GNAS gene, which encodes Gsα and other translated and untranslated products. EVIDENCE ACQUISITION A PubMed search was used to identify the available studies (main query terms: pseudohypoparathyroidism; Albright hereditary osteodystrophy; GNAS; GNAS1; progressive osseous heteroplasia). The most relevant studies until February 2011 have been included in the review. EVIDENCE SYNTHESIS AND CONCLUSIONS Despite the first description of this disorder dates back to 1942, recent findings indicating complex epigenetic alterations beside classical mutations at the GNAS complex gene, pointed out the limitation of the actual classification of the disease, resulting in incorrect genetic counselling and diagnostic procedures, as well as the gap in our actual knowledge of the pathogenesis of these disorders. This review will focus on PHP type I, in particular its diagnosis, classification, treatment, and underlying molecular alterations.
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Affiliation(s)
- Giovanna Mantovani
- Endocrinology and Diabetology Unit, Department of Medical Sciences, Università degli Studi di Milano, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca' Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy.
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Kinoshita K, Minagawa M, Takatani T, Takatani R, Ohashi M, Kohno Y. Establishment of diagnosis by bisulfite-treated methylation-specific PCR method and analysis of clinical characteristics of pseudohypoparathyroidism type 1b. Endocr J 2011; 58:879-87. [PMID: 21836370 DOI: 10.1507/endocrj.k10e-364] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Pathogenesis of pseudohypoparathyroidism type 1b (PHP-1b) is related to the loss of methylation at the GNAS exon A/B region, which is combined with epigenetic defects at other differentially methylated GNAS regions in most sporadic cases. In this study, we established a method for evaluating the methylation status of a CpG island in exon A/B using a methylation-specific polymerase chain reaction (MSPCR). We designed two primer pairs specific for the methylated and unmethylated alleles and evaluated the methylation status of GNAS exon A/B in samples from PHP-1b patients and normal controls. We examined 20 Japanese patients and 20 normal controls, and one primer set was found to be appropriate for diagnosis. Furthermore, we evaluated the clinical data of patients. Weight and height of patients were not significantly different from the normal population. Short stature (adult height ≤ 2SD) was observed in one patient and short metacarpals in two. Obesity was observed in six patients, and no patient showed ectopic subcutaneous calcification. Seven patients showed subclinical hypothyroidism because of resistance to thyroid stimulating hormone, but no patient had an abnormally low free thyroxine level, and none received oral thyroid hormone replacement. For diagnosis of PHP-1b, only clinical data is not sufficient because a few PHP-1b patients show clinical features similar to PHP-1a, and hence, molecular biology techniques are required for correct diagnosis. We concluded that MSPCR is applicable for rapid molecular diagnosis of PHP-1b.
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Affiliation(s)
- Kaori Kinoshita
- Department of Pediatrics, Graduate School of Medicine, Chiba University, Chiba, Japan.
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Jin HY, Lee BH, Choi JH, Kim GH, Kim JK, Lee JH, Yu J, Yoo JH, Ko CW, Lim HH, Chung HR, Yoo HW. Clinical characterization and identification of two novel mutations of the GNAS gene in patients with pseudohypoparathyroidism and pseudopseudohypoparathyroidism. Clin Endocrinol (Oxf) 2011; 75:207-13. [PMID: 21521295 DOI: 10.1111/j.1365-2265.2011.04026.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVE Pseudohypoparathyroidism (PHP) and pseudopseudohypoparathyroidism (PPHP) are rare disorders resulting from genetic and epigenetic aberrations in the GNAS locus. DESIGN Investigation of clinical characteristics and molecular analysis in PHP and PPHP. PATIENTS Fourteen subjects from 13 unrelated families including subjects with PPHP (n = 1), PHP-Ia (n = 6) and PHP-Ib (n = 7) were enrolled. MEASUREMENTS Clinical data, including age at presentation, presenting symptom, auxological findings, family history, presence of Albright hereditary osteodystrophy (AHO) features and hormonal and biochemical findings, were analysed. The GNAS locus was subjected to direct sequencing and methylation analysis using methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA). RESULTS Of the 13 PHP subjects, 10 (three PHP-Ia and seven PHP-Ib) presented with hypocalcemic tetany at ages ranging from 7 to 14·8 years. Subcutaneous calcification was observed as an early manifestation of AHO in one PHP-Ia patient (age, 2·9 years) and one PPHP patient (age, 7 months). Six PHP-Ia and one PPHP harboured four different heterozygous mutations within the coding region of GNAS, p.Asp189_Tyr190delinsMetfxX14, p.Val117fsX23, p.Tyr190CysfsX19, and a splicing mutation (c.659 + 1G>A), of which the latter two were novel. Five subjects with PHP-Ib exhibited complete loss of the maternal-specific methylation pattern. The remaining two PHP-Ib showed a loss of methylation of exon 1A on the maternal allele as a consequence of heterozygous 3-kb microdeletions within the STX16 gene. CONCLUSIONS GNAS mutation analyses and MS-MLPA assays are useful molecular tools for understanding the molecular bases and confirming the diagnosis of PHP and PPHP.
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Affiliation(s)
- Hye Young Jin
- Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea
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Bastepe M. The GNAS Locus: Quintessential Complex Gene Encoding Gsalpha, XLalphas, and other Imprinted Transcripts. Curr Genomics 2011; 8:398-414. [PMID: 19412439 PMCID: PMC2671723 DOI: 10.2174/138920207783406488] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2007] [Revised: 09/22/2007] [Accepted: 09/28/2007] [Indexed: 12/14/2022] Open
Abstract
The currently estimated number of genes in the human genome is much smaller than previously predicted. As an explanation for this disparity, most individual genes have multiple transcriptional units that represent a variety of biologically important gene products. GNAS exemplifies a gene of such complexity. One of its products is the alpha-subunit of the stimulatory heterotrimeric G protein (Gsalpha), a ubiquitous signaling protein essential for numerous different cellular responses. Loss-of-function and gain-of-function mutations within Gsalpha-coding GNAS exons are found in various human disorders, including Albright's hereditary osteodystrophy, pseudohypoparathyroidism, fibrous dysplasia of bone, and some tumors of different origin. While Gsalpha expression in most tissues is biallelic, paternal Gsalpha expression is silenced in a small number of tissues, playing an important role in the development of phenotypes associated with GNAS mutations. Additional products derived exclusively from the paternal GNAS allele include XLalphas, a protein partially identical to Gsalpha, and two non-coding RNA molecules, the A/B transcript and the antisense transcript. The maternal GNAS allele leads to NESP55, a chromogranin-like neuroendocrine secretory protein. In vivo animal models have demonstrated the importance of each of the exclusively imprinted GNAS products in normal mammalian physiology. However, although one or more of these products are also disrupted by most naturally occurring GNAS mutations, their roles in disease pathogenesis remain unknown. To further our understanding of the significance of this gene in physiology and pathophysiology, it will be important to elucidate the cellular roles and the mechanisms regulating the expression of each GNAS product.
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Affiliation(s)
- Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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Thiele S, de Sanctis L, Werner R, Grötzinger J, Aydin C, Jüppner H, Bastepe M, Hiort O. Functional characterization of GNAS mutations found in patients with pseudohypoparathyroidism type Ic defines a new subgroup of pseudohypoparathyroidism affecting selectively Gsα-receptor interaction. Hum Mutat 2011; 32:653-60. [PMID: 21488135 DOI: 10.1002/humu.21489] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 02/09/2011] [Indexed: 01/09/2023]
Abstract
Pseudohypoparathyroidism type Ia (PHPIa) is caused by GNAS mutations leading to deficiency of the α-subunit of stimulatory G proteins (Gsα) that mediate signal transduction of G protein-coupled receptors via cAMP. PHP type Ic (PHPIc) and PHPIa share clinical features of Albright hereditary osteodystrophy (AHO); however, in vitro activity of solubilized Gsα protein is normal in PHPIc but reduced in PHPIa. We screened 32 patients classified as PHPIc for GNAS mutations and identified three mutations (p.E392K, p.E392X, p.L388R) in four unrelated families. These and one novel mutation associated with PHPIa (p.L388P) were introduced into a pcDNA3.1(-) expression vector encoding Gsα wild-type and expressed in a Gsα-null cell line (Gnas(E2-/E2-) ). To investigate receptor-mediated cAMP accumulation, we stimulated the endogenous expressed β(2) -adrenergic receptor, or the coexpressed PTH or TSH receptors, and measured the synthesized cAMP by RIA. The results were compared to receptor-independent cholera toxin-induced cAMP accumulation. Each of the mutants associated with PHPIc significantly reduced or completely disrupted receptor-mediated activation, but displayed normal receptor-independent activation. In contrast, PHPIa associated p.L388P disrupted both receptor-mediated activation and receptor-independent activation. We present a new subgroup of PHP that is caused by Gsα deficiency and selectively affects receptor coupling functions of Gsα.
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Affiliation(s)
- Susanne Thiele
- Department of Pediatrics and Adolescent Medicine, University of Lübeck, Germany.
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Bastepe M, Altug-Teber Ö, Agarwal C, Oberfield SE, Bonin M, Jüppner H. Paternal uniparental isodisomy of the entire chromosome 20 as a molecular cause of pseudohypoparathyroidism type Ib (PHP-Ib). Bone 2011; 48:659-62. [PMID: 20965295 PMCID: PMC3039090 DOI: 10.1016/j.bone.2010.10.168] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 10/12/2010] [Accepted: 10/13/2010] [Indexed: 11/30/2022]
Abstract
Pseudohypoparathyoridism type Ib (PHP-Ib) typically defines the presence of end-organ resistance to parathyroid hormone in the absence of Albright's hereditary osteodystrophy. Patients affected by this disorder present with imprinting defects in the complex GNAS locus. Microdeletions within STX16 or GNAS have been identified in familial cases with PHP-Ib, but the molecular cause of the GNAS imprinting defects in sporadic PHP-Ib cases remains poorly defined. We now report a case with sporadic PHP-Ib for whom a SNPlex analysis revealed loss of the maternal GNAS allele. Further analysis of the entire genome with a 100K SNP chip identified a paternal uniparental isodisomy affecting the entire chromosome 20 without evidence for another chromosomal abnormality. Our findings explain the observed GNAS methylation changes and the patient's hormone resistance, and furthermore suggest that chromosome 20 harbors, besides GNAS, no additional imprinted region that contributes to the clinical and laboratory phenotype.
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Affiliation(s)
- Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Özge Altug-Teber
- Department of Medical Genetics, University Clinics of Tübingen, Tübingen, Germany
| | - Chhavi Agarwal
- Pediatric Endocrinology, Diabetes and Metabolism Department of Pediatric Endocrinology, Columbia University Medical Center, New York, NY,USA
| | - Sharon E. Oberfield
- Pediatric Endocrinology, Diabetes and Metabolism Department of Pediatric Endocrinology, Columbia University Medical Center, New York, NY,USA
| | - Michael Bonin
- Department of Medical Genetics, University Clinics of Tübingen, Tübingen, Germany
| | - Harald Jüppner
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Pediatric Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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Effects of deficiency of the G protein Gsα on energy and glucose homeostasis. Eur J Pharmacol 2011; 660:119-24. [PMID: 21208600 DOI: 10.1016/j.ejphar.2010.10.105] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 09/24/2010] [Accepted: 10/12/2010] [Indexed: 02/07/2023]
Abstract
G(s)α is a ubiquitously expressed G protein α-subunit that couples receptors to the generation of intracellular cyclic AMP. The G(s)α gene GNAS is a complex gene that undergoes genomic imprinting, an epigenetic phenomenon that leads to differential expression from the two parental alleles. G(s)α is imprinted in a tissue-specific manner, being expressed primarily from the maternal allele in a small number of tissues. Albright hereditary osteodystrophy is a monogenic obesity disorder caused by heterozygous G(s)α mutations but only when the mutations are maternally inherited. Studies in mice indicate a similar parent-of-origin effect on energy and glucose metabolism, with maternal but not paternal mutations leading to obesity, reduced sympathetic nerve activity and energy expenditure, glucose intolerance and insulin resistance, with no primary effect on food intake. These effects result from G(s)α imprinting leading to severe G(s)α deficiency in one or more regions of the central nervous system, and are associated with a specific defect in melanocortins to stimulate sympathetic nerve activity and energy expenditure.
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Izzi B, Decallonne B, Devriendt K, Bouillon R, Vanderschueren D, Levtchenko E, de Zegher F, Van den Bruel A, Lambrechts D, Van Geet C, Freson K. A new approach to imprinting mutation detection in GNAS by Sequenom EpiTYPER system. Clin Chim Acta 2010; 411:2033-9. [PMID: 20807523 DOI: 10.1016/j.cca.2010.08.034] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 08/19/2010] [Accepted: 08/24/2010] [Indexed: 11/28/2022]
Abstract
BACKGROUND Pseudohypoparathyroidism type Ib (PHPIb) results from abnormal imprinting of GNAS. Familial and sporadic forms of PHPIb have distinct GNAS imprinting patterns: familial PHPIb patients have an exon A/B-only imprinting defect and an intragenic STX16 deletion, whereas sporadic PHPIb cases have abnormal imprinting of the three differentially methylated regions (DMRs) in GNAS without the STX16 deletion. Overall GNAS methylation defects have recently been detected in some PHPIa patients. METHODS This study describes the first quantitative methylation analysis of multiple CpG sites for three different GNAS DMRs using the Sequenom EpiTYPER in 35 controls, 12 PHPIb patients, 2 PHPIa patients and 2 patients without parathormone (PTH) resistance but having only hypocalcemia and hyperphosphatemia. RESULTS All patients have GNAS methylation defects typically with NESP hypermethylation versus XL and exon A/B hypomethylation while the imprinting of SNURF/SNRPN was normal. PHPIa patients showed an abnormal methylation in the three DMRs of GNAS. For the first time, a marked abnormal GNAS methylation was also found in 2 patients without PTH resistance but having hypocalcemia and hyperphosphatemia. CONCLUSIONS The Sequenom EpiTYPER proves to be very sensitive in detecting DNA methylation changes. Our analysis also suggests that GNAS imprinting defects might be more frequent and diverse than previously thought.
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Affiliation(s)
- Benedetta Izzi
- Center for Molecular and Vascular Biology, University of Leuven, Leuven, 3000, Belgium
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Fernández-Rebollo E, Lecumberri B, Garin I, Arroyo J, Bernal-Chico A, Goñi F, Orduña R, Castaño L, de Nanclares GP. New mechanisms involved in paternal 20q disomy associated with pseudohypoparathyroidism. Eur J Endocrinol 2010; 163:953-62. [PMID: 20837711 DOI: 10.1530/eje-10-0435] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
PURPOSE Type I pseudohypoparathyroidism (PHP-I) can be subclassified into Ia and Ib, depending on the presence or absence of Albright's hereditary osteodystrophy's phenotype, diminished α-subunit of the stimulatory G protein (G(s)α) activity and multihormonal resistance. Whereas PHP-Ia is mainly associated with heterozygous inactivating mutations in G(s)α-coding exons of GNAS, PHP-Ib is caused by imprinting defects of GNAS. To date, just one patient with PHP and complete paternal uniparental disomy (UPD) has been described. We sought to identify the underlining molecular defect in twenty patients with parathyroid hormone resistance, hypocalcemia and hyperphosphatemia, and abnormal methylation pattern at GNAS locus. METHODS Microsatellite typing and comparative genome hybridization were performed for proband and parents. RESULTS We describe four patients with partial paternal UPD of chromosome 20 involving pat20qUPD in one case, from 20q13.13-qter in two cases, and pat20p heterodisomy plus interstitial 20q isodisomy in one patient. CONCLUSIONS These observations demonstrate that mitotic recombination of chromosome 20 can also give rise to UPD and PHP, a situation similar to other imprinting disorders, such as Beckwith-Wiedemann syndrome or neonatal diabetes.
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Affiliation(s)
- Eduardo Fernández-Rebollo
- Endocrinology and Diabetes Research Group, Molecular Genetics Laboratory, Hospital de Cruces, 48903 Barakaldo, Bizkaia, Spain
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Crane JL, Shamblott MJ, Axelman J, Hsu S, Levine MA, Germain-Lee EL. Imprinting status of Galpha(s), NESP55, and XLalphas in cell cultures derived from human embryonic germ cells: GNAS imprinting in human embryonic germ cells. Clin Transl Sci 2010; 2:355-60. [PMID: 20443919 DOI: 10.1111/j.1752-8062.2009.00148.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
GNAS is a complex gene that through use of alternative first exons encodes signaling proteins Galpha(s) and XLalphas plus neurosecretory protein NESP55. Tissue-specific expression of these proteins is regulated through reciprocal genomic imprinting in fully differentiated and developed tissue. Mutations in GNAS account for several human disorders, including McCune-Albright syndrome and Albright hereditary osteodystrophy, and further knowledge of GNAS imprinting may provide insights into variable phenotypes of these disorders. We therefore analyzed expression of Galpha(s), NESP55, and XLalphas prior to tissue differentiation in cell cultures derived from human primordia germ cells. We found that the expression of Galpha(s) was biallelic (maternal allele: 52.6%+/- 2.5%; paternal allele: 47.2%+/- 2.5%; p= 0.07), whereas NESP55 was expressed preferentially from the maternal allele (maternal allele: 81.9%+/- 10%; paternal allele: 18.1%+/- 10%; p= 0.002) and XLalphas was preferentially expressed from the paternal allele (maternal allele: 2.7%+/- 0.3%; paternal allele: 97.3%+/- 0.3%; p= 0.007). These results demonstrate that imprinting of NESP55 occurs very early in development, although complete imprinting appears to take place later than 5-11 weeks postfertilization, and that imprinting of XLalphas occurs very early postfertilization. By contrast, imprinting of Galpha(s) most likely occurs after 11 weeks postfertilization and after tissue differentiation.
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Affiliation(s)
- Janet L Crane
- Department of Pediatrics, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Shoemaker R, Wang W, Zhang K. Mediators and dynamics of DNA methylation. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2010; 3:281-98. [PMID: 20878927 DOI: 10.1002/wsbm.124] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
As an inherited epigenetic marker occurring mainly on cytosines at CpG dinucleotides, DNA methylation occurs across many higher eukaryotic organisms. Looking at methylation patterns genome-wide classifies cell types uniquely and in several cases discriminates between healthy and cancerous cell types. DNA methylation can occur allele-specifically, which allows the cellular regulatory machinery to recognize each allele separately. Although only a small number of allele specifically methylated (ASM) regions are known, genome-wide experiments show that ASM is prevalent throughout the human genome. These DNA methylation patterns can be modified via DNA demethylation, which is important for induced pluripotent stem reprogramming and primordial germ cells. Recent evidence shows that the protein activation-induced cytidine deaminase plays a critical role in these demethylation events. Many transcription factors mediate DNA methylation patterns. Some transcription factors bind specifically to methylated or unmethylated sequences and other transcription factors protect genomic regions (e.g., promoter regions) from nearby DNA methylation encroachment. Possibly acting as another epigenetic regulatory layer, methylated cytosines are also converted to 5-hydroxyethylcyotines, which is a new modification type whose biological significance has yet been defined.
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Affiliation(s)
- Robert Shoemaker
- Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, CA, USA
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Kelsey G. Imprinting on chromosome 20: Tissue-specific imprinting and imprinting mutations in the GNAS locus. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2010; 154C:377-86. [DOI: 10.1002/ajmg.c.30271] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Chillambhi S, Turan S, Hwang DY, Chen HC, Jüppner H, Bastepe M. Deletion of the noncoding GNAS antisense transcript causes pseudohypoparathyroidism type Ib and biparental defects of GNAS methylation in cis. J Clin Endocrinol Metab 2010; 95:3993-4002. [PMID: 20444925 PMCID: PMC2913043 DOI: 10.1210/jc.2009-2205] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
CONTEXT GNAS encodes the alpha-subunit of the stimulatory G protein as well as additional imprinted transcripts including the maternally expressed NESP55 and the paternally expressed XLalphas, antisense, and A/B transcripts. Most patients with pseudohypoparathyroidism type Ib (PHP-Ib) exhibit imprinting defects affecting the maternal GNAS allele, which are thought to reduce/abolish Gsalpha expression in renal proximal tubules and thereby cause resistance to PTH. OBJECTIVE Our objective was to define the genetic defect in a previously unreported family with autosomal dominant PHP-Ib. DESIGN AND SETTING Analyses of serum and urine chemistries and of genomic DNA and lymphoblastoid-derived RNA were conducted at a tertiary hospital and research laboratory. PATIENTS Affected individuals presented with muscle weakness and/or paresthesia and showed hypocalcemia, hyperphosphatemia, and elevated serum PTH. Obligate carriers were healthy and revealed no obvious abnormality in mineral ion homeostasis. RESULTS A novel 4.2-kb microdeletion was discovered in the affected individuals and the obligate carriers, ablating two noncoding GNAS antisense exons while preserving the NESP55 exon. On maternal transmission, the deletion causes loss of all maternal GNAS imprints, partial gain of NESP55 methylation, and PTH resistance. Paternal transmission of the mutation leads to epigenetic alterations in cis, including a partial loss of NESP55 methylation and a partial gain of A/B methylation. CONCLUSIONS The identified deletion points to a unique cis-acting element located telomeric of the NESP55 exon that is critical for imprinting both GNAS alleles. These findings provide novel insights into the molecular mechanisms underlying PHP and GNAS imprinting.
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Affiliation(s)
- Smitha Chillambhi
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, 50 Blossom Street Thier 10, Boston, Massachusetts 02114, USA
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Targeted deletion of the Nesp55 DMR defines another Gnas imprinting control region and provides a mouse model of autosomal dominant PHP-Ib. Proc Natl Acad Sci U S A 2010; 107:9275-80. [PMID: 20427744 DOI: 10.1073/pnas.0910224107] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Approximately 100 genes undergo genomic imprinting. Mutations in fewer than 10 imprinted genetic loci, including GNAS, are associated with complex human diseases that differ phenotypically based on the parent transmitting the mutation. Besides the ubiquitously expressed Gsalpha, which is of broad biological importance, GNAS gives rise to an antisense transcript and to several Gsalpha variants that are transcribed from the nonmethylated parental allele. We previously identified two almost identical GNAS microdeletions extending from exon NESP55 to antisense (AS) exon 3 (delNESP55/delAS3-4). When inherited maternally, both deletions are associated with erasure of all maternal GNAS methylation imprints and autosomal-dominant pseudohypoparathyroidism type Ib, a disorder characterized by parathyroid hormone-resistant hypocalcemia and hyperphosphatemia. As for other imprinting disorders, the mechanisms resulting in abnormal GNAS methylation are largely unknown, in part because of a paucity of suitable animal models. We now showed in mice that deletion of the region equivalent to delNESP55/delAS3-4 on the paternal allele (DeltaNesp55(p)) leads to healthy animals without Gnas methylation changes. In contrast, mice carrying the deletion on the maternal allele (DeltaNesp55(m)) showed loss of all maternal Gnas methylation imprints, leading in kidney to increased 1A transcription and decreased Gsalpha mRNA levels, and to associated hypocalcemia, hyperphosphatemia, and secondary hyperparathyroidism. Besides representing a murine autosomal-dominant pseudohypoparathyroidism type Ib model and one of only few animal models for imprinted human disorders, our findings suggest that the Nesp55 differentially methylated region is an additional principal imprinting control region, which directs Gnas methylation and thereby affects expression of all maternal Gnas-derived transcripts.
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Fernandez-Rebollo E, García-Cuartero B, Garin I, Largo C, Martínez F, Garcia-Lacalle C, Castaño L, Bastepe M, Pérez de Nanclares G. Intragenic GNAS deletion involving exon A/B in pseudohypoparathyroidism type 1A resulting in an apparent loss of exon A/B methylation: potential for misdiagnosis of pseudohypoparathyroidism type 1B. J Clin Endocrinol Metab 2010; 95:765-71. [PMID: 20008020 PMCID: PMC2840867 DOI: 10.1210/jc.2009-1581] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
CONTEXT Several endocrine diseases that share resistance to PTH are grouped under the term pseudohypoparathyroidism (PHP). Patients with PHP type Ia show additional hormone resistance, defective erythrocyte G(s)alpha activity, and dysmorphic features termed Albright's hereditary osteodystrophy (AHO). Patients with PHP-Ib show less diverse hormone resistance and normal G(s)alpha activity; AHO features are typically absent in PHP-Ib. Mutations affecting G(s)alpha coding exons of GNAS and epigenetic alterations in the same gene are associated with PHP-Ia and -Ib, respectively. The epigenetic GNAS changes in familial PHP-Ib are caused by microdeletions near or within GNAS but without involving G(s)alpha coding exons. OBJECTIVE We sought to identify the molecular defect in a patient who was diagnosed with PHP-Ia based on clinical presentation (hormone resistance and AHO) but displayed the molecular features typically associated with PHP-Ib (loss of methylation at exon A/B) without previously described genetic mutations. METHODS Microsatellite typing, comparative genome hybridization, and allelic dosage were performed for proband and her parents. RESULTS Comparative genome hybridization revealed a deletion of 30,431 bp extending from the intronic region between exons XL and A/B to intron 5. The same mutation was also demonstrated, by PCR, in the patient's mother, but polymorphism and allele dosage analyses indicated that she had this mutation in a mosaic manner. CONCLUSION We discovered a novel multiexonic GNAS deletion transmitted to our patient from her mother who is mosaic for this mutation. The deletion led to different phenotypic manifestations in the two generation and appeared, in the patient, as loss of GNAS imprinting.
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