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Liu H, Xu L, Huang H, Zhao P, Yang R, Zhou Q, Liu G. Systematic profiling of clinical missence mutation effects on the intermolecular interaction between human growth hormone and its receptor in isolated growth hormone deficiency. J Mol Graph Model 2019; 92:1-7. [PMID: 31279174 DOI: 10.1016/j.jmgm.2019.06.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 06/26/2019] [Accepted: 06/27/2019] [Indexed: 11/17/2022]
Abstract
Isolated growth hormone deficiency (IGHD) is the most common pituitary hormone deficiency and can result from congenital or acquired causes. Among the known factors, genetic mutations in human growth hormone (hGH) remain the most frequent cause of IGHD, which influence the binding of hGH to its cognate receptor (hGHbp). Although previous studies have systematically investigated the residue importance at hGH-hGHbp complex interface, the molecular role of IGHD-associated residue mutations in the complex function still remains largely unexplored. Here, a total of 21 known hGH naturally-occurring missence mutations that have been clinically observed to be involved in IGHD disorder are collected and confirmed by original literature; they effects on the conformation, energetics and dynamics of hGH-hGHbp recognition and interaction are dissected at molecular level by using atomistic dynamics simulations, binding energy calculations and fluorescence spectroscopy assays. A systematic profile of hGH-hGHbp binding response to these clinical missence mutations is created, based on which it is revealed that (i) most mutations have appreciably unfavorable effect on the binding, which potentially destabilize the complex interaction, while only very few are predicted as moderate stabilizers for the complex system, and (ii) these disease-related mutations can locate either at complex interface or in hGH protein interior far away from the interface; both can influence the complex binding through either direct interaction or indirect allostericity. Two mutations, E100K (non-interface) and G146R (interface), are identified to address potent destabilization effect on hGH-hGHbp complex system; they can reduce the complex binding affinity by 8-fold (Kd changes from 0.76 to 5.9 nM) and 46-fold (Kd changes from 0.76 to 34.7 nM), respectively.
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Affiliation(s)
- Hui Liu
- Department of Endocrinology, Fujian Provincial Maternity and Children's Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, 350001, China
| | - Liangpu Xu
- Fujian Key Laboratory for Prenatal Diagnosis and Birth Defect, Fujian Provincial Maternity and Children's Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, 350001, China
| | - Hailong Huang
- Fujian Key Laboratory for Prenatal Diagnosis and Birth Defect, Fujian Provincial Maternity and Children's Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, 350001, China
| | - Peiran Zhao
- Department of Endocrinology, Fujian Provincial Maternity and Children's Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, 350001, China
| | - Rongrong Yang
- Department of Endocrinology, Fujian Provincial Maternity and Children's Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, 350001, China
| | - Qing Zhou
- Department of Endocrinology, Fujian Provincial Maternity and Children's Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, 350001, China
| | - Guanghua Liu
- Department of Pediatrics, Fujian Provincial Maternity and Children's Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, 350001, China.
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Blum WF, Klammt J, Amselem S, Pfäffle HM, Legendre M, Sobrier ML, Luton MP, Child CJ, Jones C, Zimmermann AG, Quigley CA, Cutler GB, Deal CL, Lebl J, Rosenfeld RG, Parks JS, Pfäffle RW. Screening a large pediatric cohort with GH deficiency for mutations in genes regulating pituitary development and GH secretion: Frequencies, phenotypes and growth outcomes. EBioMedicine 2018; 36:390-400. [PMID: 30266296 PMCID: PMC6197701 DOI: 10.1016/j.ebiom.2018.09.026] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 09/14/2018] [Indexed: 11/28/2022] Open
Affiliation(s)
- Werner F Blum
- University Hospital for Children and Adolescents, University of Leipzig, Liebigstrasse 20a, 04103 Leipzig, Germany; Center of Child and Adolescent Medicine, Justus Liebig University, Feulgenstrasse 12, 35392 Giessen, Germany.
| | - Jürgen Klammt
- University Hospital for Children and Adolescents, University of Leipzig, Liebigstrasse 20a, 04103 Leipzig, Germany
| | - Serge Amselem
- Sorbonne Université, Inserm UMR_S933, Département de Génétique, Hôpital Trousseau, AP-HP, 75012 Paris, France
| | - Heike M Pfäffle
- University Hospital for Children and Adolescents, University of Leipzig, Liebigstrasse 20a, 04103 Leipzig, Germany
| | - Marie Legendre
- Sorbonne Université, Inserm UMR_S933, Département de Génétique, Hôpital Trousseau, AP-HP, 75012 Paris, France
| | - Marie-Laure Sobrier
- Sorbonne Université, Inserm UMR_S933, Département de Génétique, Hôpital Trousseau, AP-HP, 75012 Paris, France
| | - Marie-Pierre Luton
- Sorbonne Université, Inserm UMR_S933, Département de Génétique, Hôpital Trousseau, AP-HP, 75012 Paris, France
| | | | - Christine Jones
- Eli Lilly and Company, Werner-Reimers-Strasse 2-4, 61352 Bad Homburg, Germany
| | | | | | | | - Cheri L Deal
- University of Montreal and CHU Ste-Justine, Montreal, Canada
| | - Jan Lebl
- Department of Pediatrics, 2nd Faculty of Medicine, Charles University, University Hospital Motol, V Uvalu 84, 150 06 Prague, 5, Czech Republic
| | - Ron G Rosenfeld
- Department of Pediatrics, Oregon Health and Science University, Portland, USA
| | - John S Parks
- Division of Pediatric Endocrinology and Diabetes, Emory University School of Medicine, 2015 Uppergate Dr, Atlanta, GA 30322, USA
| | - Roland W Pfäffle
- University Hospital for Children and Adolescents, University of Leipzig, Liebigstrasse 20a, 04103 Leipzig, Germany
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Abstract
Research over the last 20 years has led to the elucidation of the genetic aetiologies of Isolated Growth Hormone Deficiency (IGHD) and Combined Pituitary Hormone Deficiency (CPHD). The pituitary plays a central role in growth regulation, coordinating the multitude of central and peripheral signals to maintain the body's internal balance. Naturally occurring mutation in humans and in mice have demonstrated a role for several factors in the aetiology of IGHD/CPHD. Mutations in the GH1 and GHRHR genes shed light on the phenotype and pathogenesis of IGHD whereas mutations in transcription factors such as HESX1, PROP1, POU1F1, LHX3, LHX4, GLI2 and SOX3 contributed to the understanding of CPHD. Depending upon the expression patterns of these molecules, the phenotype may consist of isolated hypopituitarism, or more complex disorders such as septo-optic dysplasia (SOD) and holoprosencephaly. Although numerous monogenic causes of growth disorders have been identified, most of the patients with IGHD/CPHD remain with an explained aetiology as shown by the relatively low mutation detection rate. The introduction of novel diagnostic approaches is now leading to the disclosure of novel genetic causes in disorders characterized by pituitary hormone defects.
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Affiliation(s)
- Mara Giordano
- Department of Health Sciences, Laboratory of Human Genetics, University of Eastern Piedmont, Novara, Italy.
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Arman A, Dündar BN, Çetinkaya E, Erzaim N, Büyükgebiz A. Novel growth hormone-releasing hormone receptor gene mutations in Turkish children with isolated growth hormone deficiency. J Clin Res Pediatr Endocrinol 2014; 6:202-8. [PMID: 25541890 PMCID: PMC4293654 DOI: 10.4274/jcrpe.1518] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
OBJECTIVE Isolated growth hormone deficiency (IGHD) is defined as a medical condition associated with growth failure due to insufficient production of GH or lack of GH action. Mutations in the gene encoding for GH-releasing hormone receptor (GHRHR) have been detected in patients with IGHD type IB. However, genetic defects on GHRHR causing IGHD in the Turkish population have not yet been reported. To identify mutations on GHRHR gene in a population of Turkish children with IGHD. METHODS Ninety-six Turkish children with IGHD were included in this study. Exon1-13 and exon/intron boundaries of GHRHR were amplified by suitable primers. The polymerase chain reaction products for GHRHR gene were sequenced with primers. RESULTS We analyzed the GHRHR gene for mutations in ninety-six patients with IGHD based on sequence results. We identified novel p.K264E, p.S317T, p.S330L, p.G369V, p.T257A and C base insertion on position 380 (c.380inserC) mutations. In 5 of the patients, the mutation was homozygote and in 1-heterozygote (p.S317T). CONCLUSION Six new missense mutations and one first case of insertion mutations for the GHRHR gene are reported.
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Affiliation(s)
- Ahmet Arman
- Marmara University Faculty of Medicine, Department of Medical Genetics, İstanbul, Turkey. E-ma-il:
| | - Bumin Nuri Dündar
- Katip Çelebi University Faculty of Medicine, Department of Pediatric Endocrinology, İzmir, Turkey
| | | | - Nilüfer Erzaim
- Yeditepe University Faculty of Medicine, Department of Genetics and Bioengineering, İstanbul, Turkey
| | - Atilla Büyükgebiz
- Bilim University Faculty of Medicine, Department of Pediatric Endocrinology, İstanbul, Turkey
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Alatzoglou KS, Webb EA, Le Tissier P, Dattani MT. Isolated growth hormone deficiency (GHD) in childhood and adolescence: recent advances. Endocr Rev 2014; 35:376-432. [PMID: 24450934 DOI: 10.1210/er.2013-1067] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The diagnosis of GH deficiency (GHD) in childhood is a multistep process involving clinical history, examination with detailed auxology, biochemical testing, and pituitary imaging, with an increasing contribution from genetics in patients with congenital GHD. Our increasing understanding of the factors involved in the development of somatotropes and the dynamic function of the somatotrope network may explain, at least in part, the development and progression of childhood GHD in different age groups. With respect to the genetic etiology of isolated GHD (IGHD), mutations in known genes such as those encoding GH (GH1), GHRH receptor (GHRHR), or transcription factors involved in pituitary development, are identified in a relatively small percentage of patients suggesting the involvement of other, yet unidentified, factors. Genome-wide association studies point toward an increasing number of genes involved in the control of growth, but their role in the etiology of IGHD remains unknown. Despite the many years of research in the area of GHD, there are still controversies on the etiology, diagnosis, and management of IGHD in children. Recent data suggest that childhood IGHD may have a wider impact on the health and neurodevelopment of children, but it is yet unknown to what extent treatment with recombinant human GH can reverse this effect. Finally, the safety of recombinant human GH is currently the subject of much debate and research, and it is clear that long-term controlled studies are needed to clarify the consequences of childhood IGHD and the long-term safety of its treatment.
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Affiliation(s)
- Kyriaki S Alatzoglou
- Developmental Endocrinology Research Group (K.S.A., E.A.W., M.T.D.), Clinical and Molecular Genetics Unit, and Birth Defects Research Centre (P.L.T.), UCL Institute of Child Health, London WC1N 1EH, United Kingdom; and Faculty of Life Sciences (P.L.T.), University of Manchester, Manchester M13 9PT, United Kingdom
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Soneda A, Adachi M, Muroya K, Asakura Y, Takagi M, Hasegawa T, Inoue H, Itakura M. Novel compound heterozygous mutations of the growth hormone-releasing hormone receptor gene in a case of isolated growth hormone deficiency. Growth Horm IGF Res 2013; 23:89-97. [PMID: 23602557 DOI: 10.1016/j.ghir.2013.03.003] [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] [Received: 09/12/2012] [Revised: 02/27/2013] [Accepted: 03/13/2013] [Indexed: 11/21/2022]
Abstract
OBJECTIVE To elucidate the pathogenesis of isolated growth hormone (GH) deficiency in a Japanese girl without consanguinity. DESIGN A 2-year-old girl of height 77.2 cm (-3.0 SD for Japanese girls) was found to have an insulin-like growth factor (IGF)-1 level of 7 ng/mL and IGF binding protein-3 (IGFBP-3) level of 0.41 μg/mL. GH responded modestly to a series of pharmacological stimulants, increasing to 2.81 ng/mL with insulin-induced hypoglycemia, 3.78 ng/mL with arginine, and 3.93 with GH-releasing hormone (GHRH). Following direct sequencing of the GHRH receptor (GHRHR) gene, evaluation by the luciferase reporter assay, immunofluorescence study, and in vitro splicing assay with minigene constructs was conducted. RESULTS Novel compound heterozygous GHRHR gene mutations were identified in the patient. A p.G136V substitution elicited no luciferase activity increment in response to GHRH stimulation, with normal membranous expression. Splicing assay demonstrated that the IVS2+3a>g mutation would lead to aberrant splicing. CONCLUSIONS A case of isolated GH deficiency due to novel GHRHR gene mutations was identified.
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Affiliation(s)
- Akiko Soneda
- Department of Endocrinology and Metabolism, Kanagawa Children's Medical Center, Japan
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A 5'UTR SNP of GHRHR locus is associated with body weight and average daily gain in Chinese cattle. Mol Biol Rep 2012; 39:10469-73. [PMID: 23053950 DOI: 10.1007/s11033-012-1927-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 10/01/2012] [Indexed: 10/27/2022]
Abstract
Growth hormone-releasing hormone receptor (GHRHR) has important functions in the regulation of the growth hormone axis and the development and proliferation of pituitary somatotropes. Moreover, some mutations in mouse GHRHR can induce the dwarfism. The objective of this paper is to reveal the association of GHRHR with growth traits in three Chinese cattle breeds, including Nanyang cattle (NY, 220), Qinchuan cattle (QC, 114), and Jiaxian cattle (JX, 142). A novel single nucleotide polymorphism (NM_181020:c.102C>T) in 5'UTR of GHRHR was identified using PCR-SSCP and DNA sequencing. The frequency of NM_181020:c.102C allele ranged from 0.926 to 0.956. We found that the locus was significantly associated with NY cattle's body weight (BW) of 6 months, with average daily gain (ADG) of 0-6 months, and as well as with ADG of 6-12 months (p < 0.05). The data suggested that the polymorphism (NM_181020:c.102C>T) of the GHRHR could be a molecular marker candidate for breeding of NY cattle in favor of BW.
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Camats N, Fernández-Cancio M, Carrascosa A, Andaluz P, Albisu MÁ, Clemente M, Gussinyé M, Yeste D, Audí L. Contribution of human growth hormone-releasing hormone receptor (GHRHR) gene sequence variation to isolated severe growth hormone deficiency (ISGHD) and normal adult height. Clin Endocrinol (Oxf) 2012; 77:564-74. [PMID: 22489751 DOI: 10.1111/j.1365-2265.2012.04410.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
OBJECTIVE Molecular causes of isolated severe growth hormone deficiency (ISGHD) in several genes have been established. The aim of this study was to analyse the contribution of growth hormone-releasing hormone receptor (GHRHR) gene sequence variation to GH deficiency in a series of prepubertal ISGHD patients and to normal adult height. DESIGN, SUBJECTS AND MEASUREMENTS A systematic GHRHR gene sequence analysis was performed in 69 ISGHD patients and 60 normal adult height controls (NAHC). Four GHRHR single-nucleotide polymorphisms (SNPs) were genotyped in 248 additional NAHC. An analysis was performed on individual SNPs and combined genotype associations with diagnosis in ISGHD patients and with height-SDS in NAHC. RESULTS Twenty-one SNPs were found. P3, P13, P15 and P20 had not been previously described. Patients and controls shared 12 SNPs (P1, P2, P4-P11, P16 and P21). Significantly different frequencies of the heterozygous genotype and alternate allele were detected in P9 (exon 4, rs4988498) and P12 (intron 6, rs35609199); P9 heterozygous genotype frequencies were similar in patients and the shortest control group (heights between -2 and -1 SDS) and significantly different in controls (heights between -1 and +2 SDS). GHRHR P9 together with 4 GH1 SNP genotypes contributed to 6·2% of height-SDS variation in the entire 308 NAHC. CONCLUSIONS This study established the GHRHR gene sequence variation map in ISGHD patients and NAHC. No evidence of GHRHR mutation contribution to ISGHD was found in this population, although P9 and P12 SNP frequencies were significantly different between ISGHD and NAHC. Thus, the gene sequence may contribute to normal adult height, as demonstrated in NAHC.
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Affiliation(s)
- Núria Camats
- Departments of Paediatrics and Paediatric Endocrinology Research Unit, Vall d'Hebron Institut de Recerca (VHIR), Hospital Vall d'Hebron, Autonomous University of Barcelona, CIBERER (Centre for Biomedical Research on Rare Diseases), Instituto de Salud Carlos III, Barcelona, Spain
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Inoue H, Kangawa N, Kinouchi A, Sakamoto Y, Kimura C, Horikawa R, Shigematsu Y, Itakura M, Ogata T, Fujieda K. Identification and functional analysis of novel human growth hormone-releasing hormone receptor (GHRHR) gene mutations in Japanese subjects with short stature. Clin Endocrinol (Oxf) 2011; 74:223-33. [PMID: 21044116 DOI: 10.1111/j.1365-2265.2010.03911.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
CONTEXT Growth hormone-releasing hormone receptor (GHRHR) gene mutations have been identified in patients of different ethnic origins with isolated GH deficiency (IGHD) type IB. However, the prevalence of these mutations in the Japanese population has yet to be fully determined. OBJECTIVES This study aimed to evaluate the contributions of GHRHR mutations to the molecular mechanism underlying short stature in Japanese subjects. DESIGN The GHRHR gene was sequenced in 127 unrelated Japanese patients with either IGHD (n = 14) or idiopathic short stature (ISS; n = 113). Sequence variants were evaluated in family members and 188 controls, and then examined in functional studies. RESULTS A novel homozygous E382E (c.1146G>A) synonymous variant, at the last base of exon 12, was identified in an IGHD family with two affected sisters. In vitro splicing studies showed this mutation to result in skipping of exon 12. In one ISS patient, a heterozygous ATG-166T>C variant was found in the distal Pit-1 P2 binding element of the GHRHR promoter. In two control subjects, a close but distinct variant, ATG-164T>C, was detected. Functional studies showed that both promoter variants diminish promoter activity by altering Pit-1 binding ability. Four missense variants were also found in both patient and control groups but had no detectable functional consequences. CONCLUSIONS The homozygous GHRHR mutation was rare, being detected in only one Japanese IGHD family. Future research is needed to clarify the genetic contributions of heterozygous functional promoter variants to GHD, ISS and normal-stature variations.
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Affiliation(s)
- Hiroshi Inoue
- Division of Genetic Information, Institute for Genome Research, The University of Tokushima, Kuramoto 3-18-15, Tokushima 770-8503, Japan.
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Abstract
Isolated growth hormone deficiency is the most common pituitary hormone deficiency and can result from congenital or acquired causes, although the majority of cases are idiopathic with no identifiable etiology. Known genes involved in the genetic etiology of isolated growth hormone deficiency include those that encode growth hormone (GH1), growth-hormone-releasing hormone receptor (GHRHR) and transcription factor SOX3. However, mutations are identified in a relatively small percentage of patients, which suggests that other, yet unidentified, genetic factors are involved. Among the known factors, heterozygous mutations in GH1 remain the most frequent cause of isolated growth hormone deficiency. The identification of mutations has clinical implications for the management of patients with this condition, as individuals with heterozygous GH1 mutations vary in phenotype and can, in some cases, develop additional pituitary hormone deficiencies. Lifelong follow-up of these patients is, therefore, recommended. Further studies in the genetic etiology of isolated growth hormone deficiency will help to elucidate mechanisms implicated in the control of growth and may influence future treatment options. Advances in pharmacogenomics will also optimize the treatment of isolated growth hormone deficiency and other conditions associated with short stature, for which recombinant human growth hormone is a licensed therapy.
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Godi M, Mellone S, Petri A, Arrigo T, Bardelli C, Corrado L, Bellone S, Prodam F, Momigliano-Richiardi P, Bona G, Giordano M. A recurrent signal peptide mutation in the growth hormone releasing hormone receptor with defective translocation to the cell surface and isolated growth hormone deficiency. J Clin Endocrinol Metab 2009; 94:3939-47. [PMID: 19622623 DOI: 10.1210/jc.2009-0833] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
CONTEXT Mutations in the GHRH receptor (GHRHR) have been detected in the familial type-IB isolated GH deficiency (IGHD-IB) inherited as an autosomal recessive disorder and characterized by a low but detectable serum GH level and good response to substitutive GH therapy. OBJECTIVE The aim of our study was the identification of mutations in sporadic patients with a IGHD-IB phenotype. SUBJECTS AND METHODS The GHRHR gene was systematically screened by DHPLC in 134 IGHD patients with no family history of the disorder or declared parental consanguinity. RESULTS We identified a novel variation, Val10Gly, within the signal peptide at the heterozygous state in three patients and in one of 1084 controls (P = 0.004), suggesting that it might contribute to IGHD. The functional analysis showed that the signal peptide is not cleaved from the mutant GHRHR, which in turn is not translocated to the cellular surface, demonstrating that 10Gly drastically affects the receptor correct processing. Because 10Gly was also present in normal-stature relatives of the patients as well as in a control, it is likely that it exerts its effects in the context of other genetic and environmental susceptibility factors. CONCLUSION At difference from previous papers reporting GHRHR mutations in familial cases with a clear recessive mode of inheritance, our study was conducted on a large sample of sporadic patients and allowed to discover a novel mechanism of the disease caused by a recurrent dominant mutation in the GHRHR signal peptide associated with incomplete penetrance.
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Affiliation(s)
- Michela Godi
- Laboratory of Human Genetics, Department of Medical Sciences and Interdisciplinary Research Center of Autoimmune Diseases, University of Eastern Piedmont, 28100 Novara, Italy
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Alatzoglou KS, Turton JP, Kelberman D, Clayton PE, Mehta A, Buchanan C, Aylwin S, Crowne EC, Christesen HT, Hertel NT, Trainer PJ, Savage MO, Raza J, Banerjee K, Sinha SK, Ten S, Mushtaq T, Brauner R, Cheetham TD, Hindmarsh PC, Mullis PE, Dattani MT. Expanding the spectrum of mutations in GH1 and GHRHR: genetic screening in a large cohort of patients with congenital isolated growth hormone deficiency. J Clin Endocrinol Metab 2009; 94:3191-9. [PMID: 19567534 DOI: 10.1210/jc.2008-2783] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
CONTEXT It is estimated that 3-30% of cases with isolated GH deficiency (IGHD) have a genetic etiology, with a number of mutations being reported in GH1 and GHRHR. The aim of our study was to genetically characterize a cohort of patients with congenital IGHD and analyze their characteristics. PATIENTS AND METHODS A total of 224 patients (190 pedigrees) with IGHD and a eutopic posterior pituitary were screened for mutations in GH1 and GHRHR. To explore the possibility of an association of GH1 abnormalities with multiple pituitary hormone deficiencies, we have screened 62 patients with either multiple pituitary hormone deficiencies (42 pedigrees), or IGHD with an ectopic posterior pituitary (21 pedigrees). RESULTS Mutations in GH1 and GHRHR were identified in 41 patients from 21 pedigrees (11.1%), with a higher prevalence in familial cases (38.6%). These included previously described and novel mutations in GH1 (C182X, G120V, R178H, IVS3+4nt, a>t) and GHRHR (W273S, R94L, R162W). Autosomal dominant, type II IGHD was the commonest form (52.4%), followed by type IB (42.8%) and type IA (4.8%). Patients with type II IGHD had highly variable phenotypes. There was no difference in the endocrinology or magnetic resonance imaging appearance between patients with and without mutations, although those with mutations presented with more significant growth failure (height, -4.7 +/- 1.6 SDS vs. -3.4 +/- 1.7 SDS) (P = 0.001). There was no apparent difference between patients with mutations in GH1 and GHRHR. CONCLUSIONS IGHD patients with severe growth failure and a positive family history should be screened for genetic mutations; the evolving endocrinopathy observed in some of these patients suggests the need for long-term follow-up.
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Affiliation(s)
- Kyriaki S Alatzoglou
- Developmental Endocrinology Research Group, Clinical and Molecular Genetics Unit, University College London Institute of Child Health, London WC1N 1EH, United Kingdom
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Chapter 3 Diseases Associated with Growth Hormone‐Releasing Hormone Receptor (GHRHR) Mutations. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2009; 88:57-84. [DOI: 10.1016/s1877-1173(09)88003-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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14
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Pereira RMC, Aguiar-Oliveira MH, Sagazio A, Oliveira CRP, Oliveira FT, Campos VC, Farias CT, Vicente TAR, Gois MB, Oliveira JLM, Marques-Santos C, Rocha IES, Barreto-Filho JAS, Salvatori R. Heterozygosity for a mutation in the growth hormone-releasing hormone receptor gene does not influence adult stature, but affects body composition. J Clin Endocrinol Metab 2007; 92:2353-7. [PMID: 17356054 DOI: 10.1210/jc.2007-0092] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Biallelic mutations in the GHRH receptor (GHRHR) gene (GHRHR) are a frequent cause of isolated GH deficiency (IGHD). Although heterozygous carriers of these mutations appear normal, we hypothesized that heterozygosity for a GHRHR mutation might be associated with a subclinical phenotype. METHODS We studied members of a large Brazilian kindred with IGHD (Itabaianinha cohort) caused by a homozygous null GHRHR mutation. We compared 76 adult subjects (age, 25-75 yr) heterozygous for the mutation (WT/MT) with 77 sex-matched controls from the same population who are homozygous for the wild-type GHRHR allele (WT/WT). RESULTS We found no difference in adult height and sd score for serum IGF-I between the two groups. Body weight, body mass index, skin folds, waist and hip circumferences, and lean mass were all reduced in WT/MT subjects. Percentage fat mass and waist/hip ratio were similar in the two groups. Fasting insulin and homeostasis model assessment of insulin resistance were lower in WT/MT. The other biochemical parameters [total and fractionated cholesterol, triglycerides, lipoprotein (a), and C-reactive protein] were not different between the two groups. CONCLUSIONS Heterozygosity for a null GHRHR mutation is not associated with reduction in adult stature or in serum IGF-I but is associated with changes in body composition and possibly an increase in insulin sensitivity. These effects do not seem to be modulated by changes in circulating IGF-I.
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Affiliation(s)
- Rossana M C Pereira
- Division of Endocrinology, Johns Hopkins University, Baltimore, MD 21287, USA
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Tao YX. Inactivating mutations of G protein-coupled receptors and diseases: Structure-function insights and therapeutic implications. Pharmacol Ther 2006; 111:949-73. [PMID: 16616374 DOI: 10.1016/j.pharmthera.2006.02.008] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2006] [Accepted: 02/21/2006] [Indexed: 12/20/2022]
Abstract
Since the discovery of the first rhodopsin mutation that causes retinitis pigmentosa in 1990, significant progresses have been made in elucidating the pathophysiology of diseases caused by inactivating mutations of G protein-coupled receptors (GPCRs). This review aims to compile the compelling evidence accumulated during the past 15 years demonstrating the etiologies of more than a dozen diseases caused by inactivating GPCR mutations. A generalized classification scheme, based on the life cycle of GPCRs, is proposed. Insights gained through detailed studies of these naturally occurring mutations into the structure-function relationship of these receptors are reviewed. Therapeutic approaches directed against the different classes of mutants are being developed. Since intracellular retention emerges as the most common defect, recent progresses aimed at correcting this defect through membrane permeable pharmacological chaperones are highlighted.
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MESH Headings
- Animals
- Diabetes Insipidus, Nephrogenic/etiology
- Dwarfism/etiology
- Humans
- Hypogonadism/etiology
- Mutation
- Obesity/etiology
- Receptor, Melanocortin, Type 1/genetics
- Receptor, Melanocortin, Type 2/genetics
- Receptor, Melanocortin, Type 3/genetics
- Receptor, Parathyroid Hormone, Type 1/genetics
- Receptors, CCR5/genetics
- Receptors, Calcium-Sensing/genetics
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/physiology
- Receptors, LHRH/genetics
- Receptors, Vasopressin/genetics
- Retinitis Pigmentosa/etiology
- Rhodopsin/genetics
- Structure-Activity Relationship
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Affiliation(s)
- Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, 213 Greene Hall, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA.
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16
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Haskin O, Lazar L, Jaber L, Salvatori R, Alba M, Kornreich L, Phillip M, Gat-Yablonski G. A new mutation in the growth hormone-releasing hormone receptor gene in two Israeli Arab families. J Endocrinol Invest 2006; 29:122-30. [PMID: 16610237 DOI: 10.1007/bf03344084] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Mutations in the GHRH receptor gene (GHRH-R) are emerging as a common cause of familial isolated GH deficiency (IGHD). DESIGN We searched for GHRH-R mutations in 10 patients with IGHD of Israeli-Arab origin, belonging to two highly consanguineous families. METHODS Analysis of the 13 coding exons, the intron-exon boundaries, and the proximal promoter of the GHRH-R was performed by denaturing gradient gel electrophoresis. Abnormally migrating bands were sequenced. The newly found mutation was inserted into GHRH-R cDNA. Wild type and mutant receptor were expressed in Chinese hamster ovary (CHO) cells, and the cAMP response to GHRH was measured. RESULTS All patients were homozygous for a novel GHRH-R missense mutation in exon 11 that replaces arginine with cysteine (R357C). Functional assay demonstrated complete inactivity of the mutant receptor in vitro. The prevalence of the mutant allele in the Israeli-Arab population was found to be 2%. All the patients had low but detectable GH reserve, proportionate short stature, and growth retardation since early childhood, with good growth response to GH treatment. Magnetic resonance imaging, performed in 3 patients, revealed a normal sized anterior pituitary in one patient evaluated at early childhood, and a borderline hypoplastic gland in the 2 patients evaluated at puberty. CONCLUSIONS We describe a novel missense mutation in the GHRH-R. The high incidence of the mutant allele in Israeli Arabs suggests that the mutation may be a common cause of familial IGHD in this population.
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Affiliation(s)
- O Haskin
- Institute for Endocrinology and Diabetes, National Center for Childhood Diabetes Petach Tikva, Israel
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17
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Font-Montgomery E, Stone KM, Weaver DD, Vance GH, Das S, Thurston VC. Clinical outcome and follow-up of the first reported case of Russell-Silver syndrome with the unique combination of maternal uniparental heterodisomy 7 and mosaic trisomy 7. ACTA ACUST UNITED AC 2005; 73:577-82. [PMID: 16007591 DOI: 10.1002/bdra.20174] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Russell-Silver syndrome (RSS) has been associated with maternal uniparental disomy (UPD) for chromosome 7 although the etiology of the syndrome is still unknown. Cases of RSS associated with maternal UPD7 have involved isodisomies, heterodisomies, and mixed isodisomy with heterodisomy simultaneously. This publication is a follow-up report of the postnatal clinical outcome of the first prenatally suspected case of combined mosaic trisomy 7 with maternal uniparental disomy of chromosome 7 (UPD7). CASE The diagnosis of RSS in the proband was suspected prenatally because trisomy 7 mosaicism (47,XX,+7[13]/46,XX[19]) and maternal uniparental heterodisomy 7 were both found in amniotic fluid cells. Cord blood karyotype analysis showed only disomic cells (46,XX[50]), whereas postpartum chorionic villus analysis was completely trisomic for chromosome 7 (47,XX,+7[19]). Postnatally, the diagnosis of RSS was confirmed by physical findings, her trisomy 7 mosaicism was confirmed by cytogenetic analysis of her skin biopsy (47,XX,+7[9]/46,XX[20]) and her UPD7 was confirmed on both peripheral blood and skin biopsy using microsatellite markers. During infancy, the proband experienced growth deficiency, persistent hypoglycemia, and psychomotor developmental delay. CONCLUSIONS Trisomic rescue as a life-saving mechanism, with subsequent chromosomal mosaicism in combination with UPD may occur more frequently in RSS than has been reported. Systematic testing of cases suspected prenatally or postnatally would be informative regarding the individual contribution of each factor. Imprinting, loss of heterozygosity for recessive genes, and mosaicism may explain the short stature, asymmetry, and the variable expression of the phenotype. The contribution of these mechanisms to the syndrome should be evaluated in these cases.
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Affiliation(s)
- Esperanza Font-Montgomery
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, USA.
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18
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Kamijo T, Hayashi Y, Seo H, Yamamoto M, Ogawa M, Choski CS, Sawant NJ, Colaco MP, Desai MP. A nonsense mutation (E72X) in growth hormone releasing hormone receptor (GHRHR) gene is the major cause of familial isolated growth hormone deficiency in Western region of India: founder effect suggested by analysis of dinucleotide repeat polymorphism close to GHRHR gene. Growth Horm IGF Res 2004; 14:394-401. [PMID: 15336233 DOI: 10.1016/j.ghir.2004.05.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2003] [Revised: 01/05/2004] [Accepted: 05/27/2004] [Indexed: 11/18/2022]
Abstract
An identical nonsense mutation (E72X) in growth hormone releasing hormone receptor (GHRHR) gene was identified in 17 patients with isolated GH deficiency belonging to one Muslim and four Hindu families residing in the Western part of India. Analysis of two dinucleotide repeat polymorphism, one at 6 kb downstream and the other at 13 kb downstream of GHRHR gene, revealed that all the patients shared the same homozygotic alleles at both loci. These results strongly indicate that the nonsense mutation occurred in a single ancestor and was subsequently transmitted to the descendants. This GHRHR mutation may be an important cause of familial IGHD in Western India and Sindh area of Pakistan as previous studies have also reported the same mutation.
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Affiliation(s)
- Takashi Kamijo
- Department of Pediatrics, Kamiida Daiichi General Hospital, Nagoya, Japan
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19
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Souza AHO, Salvatori R, Martinelli CE, Carvalho WMO, Menezes CA, Barretto ESDA, Barreto Filho JAS, Alcântara MRSD, Oliveira CRP, Alcântara PRSD, Ramalho RJR, Oliveira HA, Lima IBD, Carneiro JN, Santos MM, Gill MS, Clayton PE, Oliveira MHA. Hormônio do crescimento ou somatotrófico: novas perspectivas na deficiência isolada de GH a partir da descrição da mutação no gene do receptor do GHRH nos indivíduos da cidade de Itabaianinha, Brasil. ACTA ACUST UNITED AC 2004; 48:406-13. [PMID: 15640904 DOI: 10.1590/s0004-27302004000300013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Além de influenciar o crescimento corpóreo, o hormônio do crescimento, ou somatotrófico, desempenha importante papel no metabolismo, composição corporal, perfil lipídico, estado cardiovascular e longevidade. Seu controle é multi-regulado por hormônios, metabólitos e peptídeos hipotalâmicos. Dados sobre a Deficiência Isolada de GH (DIGH) obtidos a partir da descrição da mutação IVS1+1G®A no gene do receptor do hormônio liberador do GH (GHRH-R) em indivíduos da cidade de Itabaianinha, SE, são revisados. São abordadas novas perspectivas sobre o modelo de resistência ao GHRH, a importância do GHRH no controle da secreção de GH, a freqüência das mutações do gene do GHRH-R, a relevância diagnóstica do IGF-I e os achados metabólicos, cardiovasculares e de qualidade de vida nestes indivíduos.
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Affiliation(s)
- Anita Hermínia O Souza
- Serviço de Endocrinologia, Hospital Universitário, Universidade Federal de Sergipe, Aracaju, SE
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20
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Alba M, Hall CM, Whatmore AJ, Clayton PE, Price DA, Salvatori R. Variability in anterior pituitary size within members of a family with GH deficiency due to a new splice mutation in the GHRH receptor gene. Clin Endocrinol (Oxf) 2004; 60:470-5. [PMID: 15049962 DOI: 10.1111/j.1365-2265.2004.02003.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Mutations in the GHRH receptor (GHRHR) gene (GHRHR) cause autosomal recessive isolated GH deficiency (IGHD), and are usually associated with anterior pituitary hypoplasia (APH) (defined as pituitary height more than 2 SDS below normal). We searched for GHRHR mutations and studied pituitary morphology in three prepubertal sibs with severe IGHD, who were born from consanguineous parents. DESIGN We sequenced the 13 exons and the intron-exon boundaries of the GHRHR of the index patient. After identifying a novel mutation, we sequenced the same area in the other family members. In addition, we performed magnetic resonance imaging (MRI) study of the pituitary (at age 8, 4 and 3 years) in the three affected subjects. RESULTS The three children were homozygous for a new GHRHR mutation that alters the second base of the invariant 5' splice site (GT) of intron 12 [IVS12 + 2T-->A]. The parents and an unaffected sibling were heterozygous for the same change. MRI did not show frank APH (by height criteria) in any of the subjects: pituitary height was normal (5.6 mm, +1.8 SDS) in the oldest sibling, and it was low but not below 2 SDS by age-adjusted criteria in the second (3 mm, -1.4 SDS), and third sibling (2.8 mm, -1.7 SDS). Calculated pituitary volume was below -2 SDS in the youngest patient. CONCLUSIONS These data demonstrate that pituitary height may fall within 2 SDS from the norm in patients with severe IGHD due to a homozygous GHRHR mutation, and that pituitary size may vary within patients with identical mutations who belong to the same family.
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Affiliation(s)
- Maria Alba
- Division of Endocrinology, and The Ilyssa Center for Molecular and Cellular Endocrinology, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
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21
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Affiliation(s)
- Roberto Salvatori
- Department of Medicine, Division of Endocrinology, Johns Hopkins University School of Medicine, Baltimore MD 21287, USA.
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22
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Alba M, Salvatori R. Familial Growth Hormone Deficiency and Mutations in the GHRH Receptor Gene. VITAMINS & HORMONES 2004; 69:209-20. [PMID: 15196883 DOI: 10.1016/s0083-6729(04)69007-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Growth hormone (GH)-releasing hormone (GHRH) is necessary for the proliferation of the somatotropic cells of the anterior pituitary and the synthesis and secretion of GH. GHRH is released by the hypothalamus into the portal hypophysial circulation to bind to a membrane surface receptor [GHRH receptor (GHRHR)] expressed by the somatotropic cells. Because of the need of GHRH for GH secretion, it is to be expected that alterations in synthesis or action of GHRH would result in isolated GH deficiency (IGHD). Indeed, although GHRH gene mutations have never been reported, mutations in the GHRHR gene (GHRHR) are emerging as a relatively common cause of inherited autosomal recessive IGHD. The first human GHRHR mutations were discovered in families with a history of parental consanguinity. More recently, kindreds in which IGHD subjects are compound heterozygotes for two distinct mutations indicate that faulty GHRHR alleles may be prevalent and that these mutations may need to be suspected even in sporadic IGHD cases. Patients with two faulty GHRHR alleles have normal weight at birth. Growth failure becomes apparent during the first year of life. Biochemical studies show low serum insulin-like growth factor-1 level, and absent or markedly reduced GH response to a variety of stimuli. Magnetic resonance imaging shows hypoplasia of the anterior pituitary. In this chapter, we describe the GHRHR mutations reported to date and the phenotype of affected individuals.
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Affiliation(s)
- Maria Alba
- Department of Medicine, Division of Endocrinology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA
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Wajnrajch MP, Gertner JM, Sokoloff AS, Ten I, Harbison MD, Netchine I, Maheshwari HG, Goldstein DB, Amselem S, Baumann G, Leibel RL. Haplotype analysis of the growth hormone releasing hormone receptor locus in three apparently unrelated kindreds from the indian subcontinent with the identical mutation in the GHRH receptor. Am J Med Genet A 2003; 120A:77-83. [PMID: 12794696 DOI: 10.1002/ajmg.a.10209] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The growth hormone releasing hormone receptor (GHRHR) plays a critical role in growth. We identified three nominally unrelated kindreds harboring the identical mutation (E72X) in GHRHR, the gene that encodes GHRHR; all three families originated in the Indian subcontinent. Because of the relative geographic proximity of these populations, we employed haplotype analysis in the region of GHRHR to determine the likelihood that this mutation occurred in a common ancestor rather than having occurred on separate occasions in different individuals. Members of all three kindreds segregating the E72X mutation were genotyped for highly polymorphic dinucleotide repeat microsatellites in a 15.5 centimorgan (cM) region around GHRHR on chromosome 7p15. We conclude that the affected individuals share a common ancestor, and we use the association with linked markers to estimate the age of this unique mutation.
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Affiliation(s)
- Michael P Wajnrajch
- Division of Pediatric Endocrinology, Department of Pediatrics, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021, USA.
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25
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Affiliation(s)
- Karen Lin-Su
- Division of Pediatric Endocrinology, Weill Medical College of Cornell University, New York, USA
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Salvatori R, Aguiar-Oliveira MH, Monte LVB, Hedges L, Santos NL, Pereira RMC, Phillips JA. Detection of a recurring mutation in the human growth hormone-releasing hormone receptor gene. Clin Endocrinol (Oxf) 2002; 57:77-80. [PMID: 12100073 DOI: 10.1046/j.1365-2265.2002.01565.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE Mutations in the gene encoding for the GH-releasing hormone receptor (GHRHR) have been recently described in patients with familial isolated GH deficiency (IGHD) type IB. To date, all reported mutations have been found in kindreds sharing common ancestors. The only exception is a T to A transversion which causes a substitution of histidine for leucine in codon 144 (L144H) and creates a DraIII restriction site. This mutation was described in two families with different ethnic background residing in two different continents (Europe and North America). DESIGN We searched for GHRHR mutations in a new family with IGHD from a third continent (South America) and found the affected individuals to be homozygous for the same L144H change. We performed linkage analysis with intra- and para-genic polymorphisms to determine if the three families carrying the L144H allele are related. RESULTS Linkage analysis studies demonstrated that one of the three families does not share the same para- and intragenic GHRHR polymorphisms with the other two. CONCLUSIONS The L144H mutation has arisen at least twice and should be considered for initial genetic analysis in patients with familial IGHD in whom the a GHRHR mutation is suspected.
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Affiliation(s)
- Roberto Salvatori
- Department of Medicine and The Ilyssa Center for Molecular and Cellular Endocrinology, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
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Salvatori R, Fan X, Mullis PE, Haile A, Levine MA. Decreased expression of the GHRH receptor gene due to a mutation in a Pit-1 binding site. Mol Endocrinol 2002; 16:450-8. [PMID: 11875102 DOI: 10.1210/mend.16.3.0785] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
A variety of mutations in the gene encoding the GHRH receptor (GHRHR) that are predicted to alter protein structure or function have been recently described in patients with isolated GH deficiency type IB. In the present report we describe a patient with isolated GH deficiency type IB who was heterozygous for two novel mutations in this gene: a missense mutation in codon 329 that replaces lysine with glutamic acid (K329E) and an A-->C transversion (position -124) in one of the two sites of the promoter region that binds the pituitary-specific transcription factor Pit-1, which is required for GHRHR expression. Chinese hamster ovary cells that were transfected with a cDNA encoding the K329E GHRHR expressed the receptor but failed to show a cAMP response after treatment with GHRH, confirming the lack of functionality. To test the effect of the A-->C mutation at position -124 of the promoter, we transfected rat GH3 pituitary cells, which express endogenous Pit-1, with plasmids in which the luciferase reporter gene was under the control of either the wild-type or the mutant promoter. GH3 cells expressing the mutant promoter showed significantly less luciferase activity than cells expressing the wild-type promoter. DNA-binding studies confirmed that the A-->C base change markedly reduces DNA binding to the Pit-1 protein. These results demonstrate that mutations in the GHRHR are not limited to the coding sequence and that promoter mutations that impair Pit-1 binding can reduce expression of the GHRHR gene.
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Affiliation(s)
- Roberto Salvatori
- Division of Endocrinology, and the Ilyssa Center for Molecular and Cellular Endocrinology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
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