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Menon JC, Kumari A, Sajjan SM, Dabadghao P. Novel Mutation in CYP2R1 Causing Vitamin D-Dependent Rickets Type 1b. JCEM CASE REPORTS 2024; 2:luae024. [PMID: 38440125 PMCID: PMC10911226 DOI: 10.1210/jcemcr/luae024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Indexed: 03/06/2024]
Abstract
Monogenic forms of rickets are being increasingly recognized. However, vitamin D-dependent rickets 1b (VDDR1b) due to CYP2R1 gene mutation is exceedingly rare. We report a 4.5-year-old girl and her younger sibling who presented with clinical, radiological, and biochemical features suggestive of nutritional rickets that did not resolve despite repeated therapeutic doses of vitamin D3. This led to evaluation for resistant rickets, which revealed a novel homozygous CYP2R1 c.50_51insTCGGCGGCGC; p.Leu18ArgfsTer79 variant in the affected siblings. The children were treated with oral calcium and cholecalciferol, dose titrated to maintain serum alkaline phosphatase, 25 hydroxy vitamin D, and parathyroid hormone levels in the normal range, with good clinical and radiological response. This case highlights the importance of genetic evaluation in patients with suspected nutritional rickets who have a family history of similar illness and require higher than usual doses of vitamin D for healing or relapse on stopping treatment. To the best of our knowledge this is the first case of VDDR1b reported from Asia.
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Affiliation(s)
- Jayakrishnan C Menon
- Department of Endocrinology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh 226014, India
| | - Archana Kumari
- Department of Endocrinology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh 226014, India
| | - Shruti M Sajjan
- Department of Endocrinology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh 226014, India
| | - Preeti Dabadghao
- Department of Endocrinology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh 226014, India
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Norlin M, Wikvall K. Enzymatic activation in vitamin D signaling - Past, present and future. Arch Biochem Biophys 2023; 742:109639. [PMID: 37196753 DOI: 10.1016/j.abb.2023.109639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 05/10/2023] [Accepted: 05/14/2023] [Indexed: 05/19/2023]
Abstract
Vitamin D signaling is important in regulating calcium homeostasis essential for bone health but also displays other functions in cells of several tissues. Disturbed vitamin D signaling is linked to a large number of diseases. The multiple cytochrome P450 (CYP) enzymes catalyzing the different hydroxylations in bioactivation of vitamin D3 are crucial for vitamin D signaling and function. This review is focused on the progress achieved in identification of the bioactivating enzymes and their genes in production of 1α,25-dihydroxyvitamin D3 and other active metabolites. Results obtained on species- and tissue-specific expression, catalytic reactions, substrate specificity, enzyme kinetics, and consequences of gene mutations are evaluated. Matters of incomplete understanding regarding the physiological roles of some vitamin D hydroxylases are critically discussed and the authors will give their view of the importance of each enzyme for vitamin D signaling. Roles of different vitamin D receptors and an alternative bioactivation pathway, leading to 20-hydroxylated vitamin D3 metabolites, are also discussed. Considerable progress has been achieved in knowledge of the vitamin D3 bioactivating enzymes. Nevertheless, several intriguing areas deserve further attention to understand the pleiotropic and diverse activities elicited by vitamin D signaling and the mechanisms of enzymatic activation necessary for vitamin D-induced responses.
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Affiliation(s)
- Maria Norlin
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden.
| | - Kjell Wikvall
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
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Abdalla AT, Koedam M, Drop SLS, Boot AM, Abdullah MA, van der Eerden BCJ. Clinical presentation and molecular genetic analysis of a Sudanese family with a novel mutation in the CYP2R1 gene. Gene X 2022; 844:146809. [PMID: 35973571 DOI: 10.1016/j.gene.2022.146809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/24/2022] [Accepted: 08/10/2022] [Indexed: 11/24/2022] Open
Abstract
The aim of this study was to identify the genetic basis of two female siblings - born to consanguineous Sudanese parents - diagnosed clinically as having the rare condition of 25-hydroxylase deficiency (vitamin D-dependent rickets type 1B). The initial diagnosis was established based on clinical data, laboratory and radiological findings retrospectively. Primers for all exons (5) of human CYP2R1 (NM_024514) were generated followed by Sanger sequencing on exons 1-5 for both girls and their parents. Homozygosity for a point mutation (c.85C > T) was detected, leading to a nonsynonymous variant at position 29 in exon 1, resulting in a premature stop codon (p.Q29X). This is a previously unknown variant that leads to a severely truncated protein and predicted to be among the 0.1 % most deleterious genomic variants(CADD score 36). To our knowledge, this family represents the first case series from Sudan with a confirmed CYP2R1 gene mutation and the 6th world-wide. With the lack of genetic facilities, diagnosis should be suspected by the persistently low 25 hydroxyvitamin D level in spite of proper treatment and after ruling out liver disease and malabsorption. Patients in this case series showed healing of rickets when treated with high doses of 1,25-dihydroxyvitamin D3 (1,25(OH)D3; calcitriol) and oral calcium.
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Affiliation(s)
- Asmahan T Abdalla
- Department of Pediatrics, International University of Africa, Khartoum, Sudan.
| | - Marijke Koedam
- Department of Internal Medicine, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Sten L S Drop
- Department of Pediatrics, Division of Pediatric Endocrinology, Erasmus MC-Sophia Rotterdam, Rotterdam, The Netherlands
| | - Annemieke M Boot
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, The Netherlands
| | | | - Bram C J van der Eerden
- Department of Internal Medicine, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands.
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Bakhamis S, Imtiaz F, Ramzan K, De Vol E, Al-Sagheir O, Al-Rajhi A, Alashwal A, Bin Abbas B, Sakati N, Al-Sagheir A. 25-Hydroxylase vitamin D deficiency in 27 Saudi Arabian subjects: a clinical and molecular report on CYP2R1 mutations. Endocr Connect 2021; 10:767-775. [PMID: 34137732 PMCID: PMC8346186 DOI: 10.1530/ec-21-0102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 06/16/2021] [Indexed: 11/26/2022]
Abstract
Vitamin D deficiency remains a major cause of rickets worldwide. Nutritional factors are the major cause and less commonly, inheritance causes. Recently, CYP2R1 has been reported as a major factor for 25-hydroxylation contributing to the inherited forms of vitamin D deficiency. We conducted a prospective cohort study at King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia, to review cases with 25-hydroxylase deficiency and describe their clinical, biochemical, and molecular genetic features. We analyzed 27 patients from nine different families who presented with low 25-OH vitamin D and not responding to usual treatment. Genetic testing identified two mutations: c.367+1G>A (12/27 patients) and c.768dupT (15/27 patients), where 18 patients were homozygous for their identified mutation and 9 patients were heterozygous. Both groups had similar clinical manifestations ranging in severity, but none of the patients with the heterozygous mutation had hypocalcemic manifestations. Thirteen out of 18 homozygous patients and all the heterozygous patients responded to high doses of vitamin D treatment, but they regressed after decreasing the dose, requiring lifelong therapy. Five out of 18 homozygous patients required calcitriol to improve their biochemical data, whereas none of the heterozygous patients and patients who carried the c.367+1G>A mutation required calcitriol treatment. To date, this is the largest cohort series analyzing CYP2R1-related 25-hydroxylase deficiency worldwide, supporting its major role in 25-hydroxylation of vitamin D. It is suggested that a higher percentage of CYP2R1 mutations might be found in the Saudi population. We believe that our study will help in the diagnosis, treatment, and prevention of similar cases in the future.
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Affiliation(s)
- Sarah Bakhamis
- Department of Pediatrics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Faiqa Imtiaz
- Centre for Genomic Medicine, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Khushnooda Ramzan
- Centre for Genomic Medicine, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Edward De Vol
- Department of Biostatistics, Epidemiology & Scientific Computing, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Osamah Al-Sagheir
- Department of Medicine, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Abdulrahman Al-Rajhi
- Department of Orthopedics, King Saud University Medical City, Riyadh, Saudi Arabia
| | - Abdullah Alashwal
- Department of Pediatrics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Bassam Bin Abbas
- Department of Pediatrics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Nadia Sakati
- Department of Pediatrics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Afaf Al-Sagheir
- Department of Pediatrics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
- Correspondence should be addressed to A AlSagheir:
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Ozden A, Doneray H, Turkyilmaz A. Two novel CYP2R1 mutations in a family with vitamin D-dependent rickets type 1b. Endocrine 2021; 72:852-864. [PMID: 33715104 DOI: 10.1007/s12020-021-02670-9] [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: 12/17/2020] [Accepted: 02/24/2021] [Indexed: 10/21/2022]
Abstract
PURPOSE Vitamin D-dependent rickets type 1b (VDDR1b) is a very rare autosomal recessive disorder caused by mutations in CYP2R1 that produces 25-hydroxylase. To date only five mutations in CYP2R1 have been identified. This study has reported the genetic results and the clinical characteristics of a family with VDDR1b and compared this family to the other families with VDDR1b in literature. METHODS After two probands were diagnosed with VDDR1b, all other family members were evaluated. Serum calcium, phosphorus, alkaline phosphatase, parathyroid hormone, 25-hydroxy vitamin D, and 1.25-dihydroxy vitamin D levels were measured in all family members. All individuals were evaluated radiographically, and a genetic analysis was done in all family members. The other families with VDDR1b in literature were reviewed. RESULTS Two novel mutations [c.367 + 1G > C and p.E339Q (c.1015G > C)] were identified. The clinic and laboratory findings were strikingly different among the members of this family regardless of the mutation and the number of alleles affected. The families having different mutations in literature had also extensive variation in both the clinical and the laboratory findings. CONCLUSION The current study further expands CYP2R1 mutation spectrum. The findings of both the current and the previous studies suggest that VDDR1b is a more complex disorder than the known autosomal recessive inheritance model and the phenotype may show an extensive variation regardless of the mutation type and the gene dosage.
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Affiliation(s)
- Ayse Ozden
- Department of Pediatric Endocrinology, Erzurum Regional Training & Research Hospital, Erzurum, Turkey.
| | - Hakan Doneray
- Department of Pediatric Endocrinology, Ataturk University Faculty of Medicine, Erzurum, Turkey
- Clinical Research Development and Design Application and Research Center, Ataturk University, Erzurum, Turkey
| | - Ayberk Turkyilmaz
- Department of Medical Genetics, Erzurum Regional Training & Research Hospital, Erzurum, Turkey
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Wiedemann A, Renard E, Molin A, Weryha G, Oussalah A, Guéant JL, Feillet F. Prolonged 25-OH Vitamin D Deficiency Does Not Impair Bone Mineral Density in Adult Patients With Vitamin D 25-Hydroxylase Deficiency (CYP2R1). Calcif Tissue Int 2020; 107:191-194. [PMID: 32430692 DOI: 10.1007/s00223-020-00704-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 05/12/2020] [Indexed: 12/30/2022]
Abstract
Vitamin D-dependent rickets type 1B (VDDR1B) is an autosomal semidominant genetic disorder caused by a deficiency in CYP2R1, which encodes vitamin D 25-hydroxylase, an enzyme that plays a crucial role in the conversion of vitamin D to 25-dihydroxyvitamin D3. VDDR1B is a severe form of rickets that occurs during infancy and which is responsive to 25-OH vitamin D supplementation. We studied three adult patients from a multi-consanguineous family with VDDR1B. They have been diagnosed with pseudo-nutritional rickets and treated during their adolescence with 25-OH vitamin D. These patients stopped their treatments at the end of adolescence and were contacted 14 to 17 years later when VDDR1B diagnosis was carried out in their niece and nephews. These three patients had undetectable 25-OH vitamin D, but normal levels of plasma 1-25(OH)2 vitamin D. All patients had a hip bone mineral density and a normal vertebral despite osteoarthritis degenerative lesions which may impact BMD evaluation. These findings show that vitamin D supplementation has a questionable effect, if any, for osteoporosis prevention in adulthood in contrast to its crucial importance during infancy and adolescence.
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Affiliation(s)
- Arnaud Wiedemann
- Reference Center for Inborn Errors of Metabolism, Pediatric Unit, University Hospital of Nancy, Nancy, France.
- INSERM UMR_S 1256, Nutrition, Genetics, and Environmental Risk Exposure (NGERE), Faculty of Medicine of Nancy, University of Lorraine, Nancy, France.
| | - Emeline Renard
- Reference Center for Inborn Errors of Metabolism, Pediatric Unit, University Hospital of Nancy, Nancy, France
| | - Arnaud Molin
- Department of Genetics, University Hospital of Caen, Caen, France
| | - Georges Weryha
- Department of Endocrinology Unit, University Hospital of Nancy, Nancy, France
| | - Abderrahim Oussalah
- INSERM UMR_S 1256, Nutrition, Genetics, and Environmental Risk Exposure (NGERE), Faculty of Medicine of Nancy, University of Lorraine, Nancy, France
- Division of Biochemistry, Molecular Biology, Nutrition, and Metabolism, Department of Molecular Medicine, University Hospital of Nancy, Nancy, France
| | - Jean-Louis Guéant
- INSERM UMR_S 1256, Nutrition, Genetics, and Environmental Risk Exposure (NGERE), Faculty of Medicine of Nancy, University of Lorraine, Nancy, France
- Division of Biochemistry, Molecular Biology, Nutrition, and Metabolism, Department of Molecular Medicine, University Hospital of Nancy, Nancy, France
| | - François Feillet
- Reference Center for Inborn Errors of Metabolism, Pediatric Unit, University Hospital of Nancy, Nancy, France
- INSERM UMR_S 1256, Nutrition, Genetics, and Environmental Risk Exposure (NGERE), Faculty of Medicine of Nancy, University of Lorraine, Nancy, France
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Abstract
The term "vitamin D dependent rickets" describes a group of genetic disorders that are characterized by early-onset rickets due to the inability to maintain adequate concentrations of active forms of vitamin D or a failure to respond fully to activated vitamin D. Although the term is now admittedly a pathophysiological misnomer, there remains clinical relevance for its continued use, as patients have a lifelong "dependency" on administration of specialized regimens of vitamin D replacement. This review provides an update on the molecular bases for the three forms of vitamin D dependent rickets, and summarizes current protocols for management of affected subjects.
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Affiliation(s)
- Michael A. Levine
- Center for Bone Health and Division of Endocrinology and Diabetes, The Children's Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States
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8
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Genetic variants of mineral metabolism in health and disease. Curr Opin Nephrol Hypertens 2020; 29:387-393. [PMID: 32427690 DOI: 10.1097/mnh.0000000000000612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Disturbances in mineral metabolism are common among individuals with chronic kidney disease and have consistently been associated with cardiovascular and bone disease. The current review aims to describe the current knowledge of the genetic aspects of mineral metabolism disturbances and to suggest directions for future studies to uncover the cause and pathogenesis of chronic kidney disease - mineral bone disorder. RECENT FINDINGS The most severe disorders of mineral metabolism are caused by highly penetrant, rare, single-gene disruptive mutations. More recently, genome-wide association studies (GWAS) have made an important contribution to our understanding of the genetic determinants of circulating levels of 25-hydroxyvitamin D, calcium, phosphorus, fibroblast growth factor-23, parathyroid hormone, fetuin-A and osteoprotegerin. Although the majority of these genes are known members of mineral homeostasis pathways, GWAS with larger sample sizes have enabled the discovery of many genes not known to be involved in the regulation of mineral metabolism. SUMMARY GWAS have enabled remarkable developments in our ability to discover the genetic basis of mineral metabolism disturbances. Although we are far from using these findings to inform clinical practice, we are gaining understanding of novel biological mechanisms and providing insight into ethnic variation in these traits.
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Casella A, Long C, Zhou J, Lai M, O’Lear L, Caplan I, Levine MA, Roizen JD. Differential Frequency of CYP2R1 Variants Across Populations Reveals Pathway Selection for Vitamin D Homeostasis. J Clin Endocrinol Metab 2020; 105:dgaa056. [PMID: 32115644 PMCID: PMC7096315 DOI: 10.1210/clinem/dgaa056] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 02/05/2020] [Indexed: 12/31/2022]
Abstract
CONTEXT Normal vitamin D homeostasis is necessary to ensure optimal mineral metabolism. Dietary insufficiency of vitamin D and the lack of sunlight each have well understood roles in vitamin D deficiency; however, the extent to which common genetic variations in vitamin D metabolizing enzymes contribute to alterations in vitamin D homeostasis remains uncertain. OBJECTIVE To examine the possibility that common coding variation in vitamin D metabolizing enzymes alters vitamin D homeostasis we determined the effect of 44 nonsynonymous polymorphisms in CYP2R1, the vitamin D 25-hydroxylase, on enzyme function. RESULTS Twenty-one of these polymorphisms decreased activity, while 2 variants increased activity. The frequency of CYP2R1 alleles with decreased 25-hydroxylase activity is 3 in every 1000 Caucasians and 7 in every 1000 African Americans. In populations where exposure to sunlight is high, alleles with decreased function occur at a frequency as high as 8%. The pattern of selected variation as compared to nonselected variation is consistent with it being the result of positive selection for nonfunctional alleles closer to the equator. To examine this possibility, we examined the variation pattern in another protein in the vitamin D pathway, the vitamin D binding protein (GC protein). The pattern of selected variation in the GC protein as compared to nonselected variation is also consistent with it being the result of positive selection for nonfunctional alleles closer to the equator. CONCLUSIONS CYP2R1 polymorphisms have important effects on vitamin D homeostasis, and the geographic variability of CYP2R1 alleles represents an adaptation to differential exposures to UVB irradiation from sunlight.
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Affiliation(s)
- Alex Casella
- Division of Endocrinology and Diabetes, Department of Pediatrics, Children’s Hospital of Pennsylvania, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Caela Long
- Division of Endocrinology and Diabetes, Department of Pediatrics, Children’s Hospital of Pennsylvania, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Jingman Zhou
- Spark Therapeutics, Inc, Philadelphia, Pennsylvania
| | - Meizan Lai
- Division of Endocrinology and Diabetes, Department of Pediatrics, Children’s Hospital of Pennsylvania, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Lauren O’Lear
- Division of Endocrinology and Diabetes, Department of Pediatrics, Children’s Hospital of Pennsylvania, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Ilana Caplan
- Division of Endocrinology and Diabetes, Department of Pediatrics, Children’s Hospital of Pennsylvania, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Michael A Levine
- Division of Endocrinology and Diabetes, Department of Pediatrics, Children’s Hospital of Pennsylvania, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Jeffrey D Roizen
- Division of Endocrinology and Diabetes, Department of Pediatrics, Children’s Hospital of Pennsylvania, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
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Bahrami A, Mehramiz M, Ghayour-Mobarhan M, Bahrami-Taghanaki H, Sadeghi Ardekani K, Tayefi M, Sadeghzade M, Rashidmayvan M, Safari Ghalezou M, Ferns GA, Avan A, Sadeghnia HR. A genetic variant in the cytochrome P450 family 2 subfamily R member 1 determines response to vitamin D supplementation. Clin Nutr 2019; 38:676-681. [DOI: 10.1016/j.clnu.2018.03.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Revised: 03/14/2018] [Accepted: 03/31/2018] [Indexed: 12/31/2022]
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Teshima T, Kurita S, Sasaki T, Matsumoto H, Niina A, Abe D, Kanno N, Koyama H. A genetic variant of CYP2R1 identified in a cat with type 1B vitamin D-dependent rickets: a case report. BMC Vet Res 2019; 15:62. [PMID: 30777056 PMCID: PMC6378717 DOI: 10.1186/s12917-019-1784-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 01/16/2019] [Indexed: 11/24/2022] Open
Abstract
Background Vitamin D-dependent rickets is rare in animals and humans. Several types of this condition are associated with genetic variants related to vitamin D metabolism. This is the first report of type 1B vitamin D-dependent rickets in a cat. Case presentation Here, we describe the case of a 3-month-old female domestic short-haired cat previously fed on commercial kitten food that presented at our clinic with seizures, lethargy, and generalized pain. Serum and ionized calcium concentrations and 1,25-dihydroxycholecalciferol in this cat were low, and radiographs showed skeletal demineralization and abnormally wide growth plates on the long bones. Initially, simple vitamin D deficiency was suspected; however, the cat’s profile, which included fed a well-balanced commercial diet, together with the findings of additional laboratory tests and the cat’s unresponsiveness to various treatments, raised the suspicion of vitamin D-dependent rickets. Examination of the DNA sequences of CYP2R1 and CYP27B1 genes, which are genes linked with vitamin D metabolism, showed a CYP2R1 frameshift mutation in exon 5 (where T is deleted at position c.1386). This mutation alters the amino acid sequence from position 462, while the stop codon introduced at position 481 prematurely truncates the 501 amino acid full-length protein. With this knowledge, a new treatment regime based on a standard dose of calcitriol was started and this markedly improved the cat’s condition. Conclusions To the best of our knowledge, the present case is the first description of type 1B vitamin D-dependent rickets linked with a genetic variant of CYP2R1 in a cat. Electronic supplementary material The online version of this article (10.1186/s12917-019-1784-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Takahiro Teshima
- Laboratory of Veterinary Internal Medicine, Department of Veterinary Clinical Medicine, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo, 180-8602, Japan.
| | - Sena Kurita
- Laboratory of Veterinary Clinical Pathology, Department of Veterinary Clinical Medicine, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo, 180-8602, Japan
| | - Takashi Sasaki
- Animal Research Center, Sapporo Medical University School Medicine, S-1 W-17, Chuo-ku, Sapporo, Hokkaido, 060-8556, Japan
| | - Hirotaka Matsumoto
- Laboratory of Veterinary Internal Medicine, Department of Veterinary Clinical Medicine, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo, 180-8602, Japan
| | - Ayaka Niina
- Laboratory of Veterinary Internal Medicine, Department of Veterinary Clinical Medicine, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo, 180-8602, Japan
| | - Daijiro Abe
- Veterinary Medical Teaching Hospital, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo, 180-8602, Japan
| | - Nobuo Kanno
- Laboratory of Veterinary Surgery, Department of Veterinary Clinical Medicine, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo, 180-8602, Japan
| | - Hidekazu Koyama
- Laboratory of Veterinary Internal Medicine, Department of Veterinary Clinical Medicine, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo, 180-8602, Japan
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Michałus I, Rusińska A. Rare, genetically conditioned forms of rickets: Differential diagnosis and advances in diagnostics and treatment. Clin Genet 2018; 94:103-114. [DOI: 10.1111/cge.13229] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Revised: 02/01/2018] [Accepted: 02/02/2018] [Indexed: 12/21/2022]
Affiliation(s)
- I. Michałus
- Department of Propedeutics Pediatrics and Bone Metabolic Diseases; Medical University of Lodz; Lodz Poland
| | - A. Rusińska
- Department of Propedeutics Pediatrics and Bone Metabolic Diseases; Medical University of Lodz; Lodz Poland
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13
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Abstract
Rickets is a bone disease associated with abnormal serum calcium and phosphate levels. The clinical presentation is heterogeneous and depends on the age of onset and pathogenesis but includes bowing deformities of the legs, short stature and widening of joints. The disorder can be caused by nutritional deficiencies or genetic defects. Mutations in genes encoding proteins involved in vitamin D metabolism or action, fibroblast growth factor 23 (FGF23) production or degradation, renal phosphate handling or bone mineralization have been identified. The prevalence of nutritional rickets has substantially declined compared with the prevalence 200 years ago, but the condition has been re-emerging even in some well-resourced countries; prematurely born infants or breastfed infants who have dark skin types are particularly at risk. Diagnosis is usually established by medical history, physical examination, biochemical tests and radiography. Prevention is possible only for nutritional rickets and includes supplementation or food fortification with calcium and vitamin D either alone or in combination with sunlight exposure. Treatment of typical nutritional rickets includes calcium and/or vitamin D supplementation, although instances infrequently occur in which phosphate repletion may be necessary. Management of heritable types of rickets associated with defects in vitamin D metabolism or activation involves the administration of vitamin D metabolites. Oral phosphate supplementation is usually indicated for FGF23-independent phosphopenic rickets, whereas the conventional treatment of FGF23-dependent types of rickets includes a combination of phosphate and activated vitamin D; an anti-FGF23 antibody has shown promising results and is under further study.
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Jones G, Kottler ML, Schlingmann KP. Genetic Diseases of Vitamin D Metabolizing Enzymes. Endocrinol Metab Clin North Am 2017; 46:1095-1117. [PMID: 29080636 DOI: 10.1016/j.ecl.2017.07.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Vitamin D metabolism involves 3 highly specific cytochrome P450 (CYP) enzymes (25-hydroxylase, 1α-hydroxylase, and 24-hydroxylase) involved in the activation of vitamin D3 to the hormonal form, 1,25-(OH)2D3, and the inactivation of 1,25-(OH)2D3 to biliary excretory products. Mutations of the activating enzymes CYP2R1 and CYP27B1 cause lack of normal 1,25-(OH)2D3 synthesis and result in rickets whereas mutations of the inactivating enzyme CYP24A1 cause build-up of excess 1,25-(OH)2D3 and result in hypercalcemia, nephrolithiasis, and nephrocalcinosis. This article reviews the literature for 3 clinical conditions. Symptoms, diagnosis, treatment, and management of vitamin D-dependent rickets and idiopathic infantile hypercalcemia are discussed.
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Affiliation(s)
- Glenville Jones
- Department of Biomedical and Molecular Sciences, Queen's University, Room 650, Botterell Hall, Kingston, ON K7L 3N6, Canada.
| | - Marie Laure Kottler
- Department of Genetics, University de Basse-Normandie, National Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Caen University Hospital, Avenue de la Côte de Nacre, 14033 Caen, France; Team 7450 BIOTARGEN, Caen-Normandy University, Esplanade de la Paix, 14032 Caen, France
| | - Karl Peter Schlingmann
- Department of General Pediatrics, University Children's Hospital, Waldeyerstr. 22, D-48149 Muenster, Germany
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15
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Abstract
Rickets is a metabolic bone disease that develops as a result of inadequate mineralization of growing bone due to disruption of calcium, phosphorus and/or vitamin D metabolism. Nutritional rickets remains a significant child health problem in developing countries. In addition, several rare genetic causes of rickets have also been described, which can be divided into two groups. The first group consists of genetic disorders of vitamin D biosynthesis and action, such as vitamin D-dependent rickets type 1A (VDDR1A), vitamin D-dependent rickets type 1B (VDDR1B), vitamin D-dependent rickets type 2A (VDDR2A), and vitamin D-dependent rickets type 2B (VDDR2B). The second group involves genetic disorders of excessive renal phosphate loss (hereditary hypophosphatemic rickets) due to impairment in renal tubular phosphate reabsorption as a result of FGF23-related or FGF23-independent causes. In this review, we focus on clinical, laboratory and genetic characteristics of various types of hereditary rickets as well as differential diagnosis and treatment approaches.
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Affiliation(s)
- Sezer Acar
- Dokuz Eylül University Faculty of Medicine, Department of Pediatric Endocrinology, İzmir, Turkey
| | - Korcan Demir
- Dokuz Eylül University Faculty of Medicine, Department of Pediatric Endocrinology, İzmir, Turkey
| | - Yufei Shi
- King Faisal Specialist Hospital & Research Centre, Department of Genetics, Riyadh, Saudi Arabia
,* Address for Correspondence: King Faisal Specialist Hospital & Research Centre, Department of Genetics, Riyadh, Saudi Arabia E-mail:
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16
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Thacher TD, Levine MA. CYP2R1 mutations causing vitamin D-deficiency rickets. J Steroid Biochem Mol Biol 2017; 173:333-336. [PMID: 27473561 DOI: 10.1016/j.jsbmb.2016.07.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 07/13/2016] [Accepted: 07/26/2016] [Indexed: 11/28/2022]
Abstract
CYP2R1 is the principal hepatic 25-hydroxylase responsible for the hydroxylation of parent vitamin D to 25-hydroxyvitamin D [25(OH)D]. Serum concentrations of 25(OH)D reflect vitamin D status, because 25(OH)D is the major circulating metabolite of vitamin D. The 1α-hydroxylation of 25(OH)D in the kidney by CYP27B1 generates the fully active vitamin D metabolite, 1,25-dihydroxyvitamin D (1,25(OH)2D). The human CYP2R1 gene, located at 11p15.2, has five exons, coding for an enzyme with 501 amino acids. In Cyp2r1-/- knockout mice, serum 25(OH)D levels were reduced by more than 50% compared wild-type mice. Genetic polymorphisms of CYP2R1 account for some of the individual variability of circulating 25(OH)D values in the population. We review the evidence that inactivating mutations in CYP2R1 can lead to a novel form of vitamin D-deficiency rickets resulting from impaired 25-hydroxylation of vitamin D. We sequenced the promoter, exons and intron-exon flanking regions of the CYP2R1 gene in members of 12 Nigerian families with rickets in more than one family member. We found missense mutations (L99P and K242N) in affected members of 2 of 12 families. The L99P mutation had previously been reported as a homozygous defect in an unrelated child of Nigerian origin with rickets. In silico analyses predicted impaired CYP2R1 folding or reduced interaction with substrate vitamin D by L99P and K242N mutations, respectively. In vitro studies of the mutant CYP2R1 proteins in HEK293 cells confirmed normal expression levels but completely absent or markedly reduced 25-hydroxylase activity by the L99P and K242N mutations, respectively. Heterozygous subjects had more moderate biochemical and clinical features of vitamin D deficiency than homozygous subjects. After an oral bolus dose of 50,000 IU of vitamin D2 or vitamin D3, heterozygous subjects had lower increases in serum 25(OH)D than control subjects, and homozygous subjects had minimal increases, supporting a semidominant inheritance of these mutations. No CYP2R1 mutations were found in 27 Nigerian children with sporadic rickets, a cohort of 50 unrelated Nigerian subjects, or in 628 unrelated subjects in the 1000 Genomes Project. We conclude that mutations in CYP2R1 are responsible for an atypical form of vitamin D-deficiency rickets, which has been classified as vitamin D dependent rickets type 1B (VDDR1B, MIM 600081).
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Affiliation(s)
- Tom D Thacher
- Department of Family Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
| | - Michael A Levine
- Department of Pediatrics, University of Pennsylvania Perelman School of Medicine and The Children's Hospital of Philadelphia, 34th & Civic Center Blvd, Philadelphia, PA, 19104, USA.
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17
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Molin A, Wiedemann A, Demers N, Kaufmann M, Do Cao J, Mainard L, Dousset B, Journeau P, Abeguile G, Coudray N, Mittre H, Richard N, Weryha G, Sorlin A, Jones G, Kottler ML, Feillet F. Vitamin D-Dependent Rickets Type 1B (25-Hydroxylase Deficiency): A Rare Condition or a Misdiagnosed Condition? J Bone Miner Res 2017; 32:1893-1899. [PMID: 28548312 DOI: 10.1002/jbmr.3181] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 05/22/2017] [Accepted: 05/25/2017] [Indexed: 11/05/2022]
Abstract
Vitamin D requires a two-step activation by hydroxylation: The first step is catalyzed by hepatic 25-hydroxylase (CYP2R1, 11p15.2) and the second one is catalyzed by renal 1α-hydroxylase (CYP27B1, 12q13.1), which produces the active hormonal form of 1,25-(OH)2 D. Mutations of CYP2R1 have been associated with vitamin D-dependent rickets type 1B (VDDR1B), a very rare condition that has only been reported to affect 4 families to date. We describe 7 patients from 2 unrelated families who presented with homozygous loss-of-function mutations of CYP2R1. Heterozygous mutations were present in their normal parents. We identified a new c.124_138delinsCGG (p.Gly42_Leu46delinsArg) variation and the previously published c.296T>C (p.Leu99Pro) mutation. Functional in vitro studies confirmed loss-of-function enzymatic activity in both cases. We discuss the difficulties in establishing the correct diagnosis and the specific biochemical pattern, namely, very low 25-OH-D suggestive of classical vitamin D deficiency, in the face of normal/high concentrations of 1,25-(OH)2 D. Siblings exhibited the three stages of rickets based on biochemical and radiographic findings. Interestingly, adult patients were able to maintain normal mineral metabolism without vitamin D supplementation. One index case presented with a partial improvement with 1alfa-hydroxyvitamin D3 or alfacalcidol (1α-OH-D3 ) treatment, and we observed a dramatic increase in the 1,25-(OH)2 D serum concentration, which indicated the role of accessory 25-hydroxylase enzymes. Lastly, in patients who received calcifediol (25-OH-D3 ), we documented normal 24-hydroxylase activity (CYP24A1). For the first time, and according to the concept of personalized medicine, we demonstrate dramatic improvements in patients who were given 25-OH-D therapy (clinical symptoms, biochemical data, and bone densitometry). In conclusion, the current study further expands the CYP2R1 mutation spectrum. We note that VDDR1B could be easily mistaken for classical vitamin D deficiency. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Arnaud Molin
- CHU de Caen, Department of Genetics, Molecular Genetics Laboratory and Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Caen, France.,Université Caen Normandie, Medical School, Caen, France.,BioTARGEN, Université Caen Normandie, Caen, France.,OeReCa, Université Caen Normandie, Caen, France
| | - Arnaud Wiedemann
- CHU de Nancy, Department of Pediatrics and Reference Center for Rare Hereditary Diseases of Metabolism, Vandoeuvre-lès-Nancy, France.,Université de Lorraine, Medical School, Vandoeuvre-lès-Nancy, France
| | - Nick Demers
- Queen's University, Department of Biomedical and Molecular Sciences, Kingston, Canada
| | - Martin Kaufmann
- Queen's University, Department of Biomedical and Molecular Sciences, Kingston, Canada
| | - Jérémy Do Cao
- CHU de Nancy, Department of Pediatrics and Reference Center for Rare Hereditary Diseases of Metabolism, Vandoeuvre-lès-Nancy, France.,Université de Lorraine, Medical School, Vandoeuvre-lès-Nancy, France
| | - Laurent Mainard
- Université de Lorraine, Medical School, Vandoeuvre-lès-Nancy, France.,CHU de Nancy, Department of Radiology, Vandoeuvre-lès-Nancy, France
| | - Brigitte Dousset
- CHU de Nancy, Department of Biochemistry, Vandoeuvre-lès-Nancy, France
| | - Pierre Journeau
- Université de Lorraine, Medical School, Vandoeuvre-lès-Nancy, France.,CHU de Nancy, Department of Orthopedic Pediatric Surgery, Vandoeuvre-lès-Nancy, France
| | - Geneviève Abeguile
- CHU de Caen, Department of Genetics, Molecular Genetics Laboratory and Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Caen, France
| | - Nadia Coudray
- CHU de Caen, Department of Genetics, Molecular Genetics Laboratory and Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Caen, France
| | - Hervé Mittre
- CHU de Caen, Department of Genetics, Molecular Genetics Laboratory and Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Caen, France.,Université Caen Normandie, Medical School, Caen, France.,OeReCa, Université Caen Normandie, Caen, France
| | - Nicolas Richard
- CHU de Caen, Department of Genetics, Molecular Genetics Laboratory and Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Caen, France.,BioTARGEN, Université Caen Normandie, Caen, France
| | - Georges Weryha
- Université de Lorraine, Medical School, Vandoeuvre-lès-Nancy, France.,CHU de Nancy, Department of Endocrinology, Vandoeuvre-lès-Nancy, France
| | - Arthur Sorlin
- CHU de Nancy, Department of Genetics, Vandoeuvre-lès-Nancy, France
| | - Glenville Jones
- Queen's University, Department of Biomedical and Molecular Sciences, Kingston, Canada
| | - Marie-Laure Kottler
- CHU de Caen, Department of Genetics, Molecular Genetics Laboratory and Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Caen, France.,Université Caen Normandie, Medical School, Caen, France.,BioTARGEN, Université Caen Normandie, Caen, France
| | - Francois Feillet
- CHU de Nancy, Department of Pediatrics and Reference Center for Rare Hereditary Diseases of Metabolism, Vandoeuvre-lès-Nancy, France.,Université de Lorraine, Medical School, Vandoeuvre-lès-Nancy, France.,INSERM, U954 Nutrition - génétique et exposition aux risques environnementaux, Vandoeuvre-lès-Nancy, France
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18
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Manousaki D, Dudding T, Haworth S, Hsu YH, Liu CT, Medina-Gómez C, Voortman T, van der Velde N, Melhus H, Robinson-Cohen C, Cousminer DL, Nethander M, Vandenput L, Noordam R, Forgetta V, Greenwood CMT, Biggs ML, Psaty BM, Rotter JI, Zemel BS, Mitchell JA, Taylor B, Lorentzon M, Karlsson M, Jaddoe VVW, Tiemeier H, Campos-Obando N, Franco OH, Utterlinden AG, Broer L, van Schoor NM, Ham AC, Ikram MA, Karasik D, de Mutsert R, Rosendaal FR, den Heijer M, Wang TJ, Lind L, Orwoll ES, Mook-Kanamori DO, Michaëlsson K, Kestenbaum B, Ohlsson C, Mellström D, de Groot LCPGM, Grant SFA, Kiel DP, Zillikens MC, Rivadeneira F, Sawcer S, Timpson NJ, Richards JB. Low-Frequency Synonymous Coding Variation in CYP2R1 Has Large Effects on Vitamin D Levels and Risk of Multiple Sclerosis. Am J Hum Genet 2017; 101:227-238. [PMID: 28757204 PMCID: PMC5544392 DOI: 10.1016/j.ajhg.2017.06.014] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 06/29/2017] [Indexed: 12/30/2022] Open
Abstract
Vitamin D insufficiency is common, correctable, and influenced by genetic factors, and it has been associated with risk of several diseases. We sought to identify low-frequency genetic variants that strongly increase the risk of vitamin D insufficiency and tested their effect on risk of multiple sclerosis, a disease influenced by low vitamin D concentrations. We used whole-genome sequencing data from 2,619 individuals through the UK10K program and deep-imputation data from 39,655 individuals genotyped genome-wide. Meta-analysis of the summary statistics from 19 cohorts identified in CYP2R1 the low-frequency (minor allele frequency = 2.5%) synonymous coding variant g.14900931G>A (p.Asp120Asp) (rs117913124[A]), which conferred a large effect on 25-hydroxyvitamin D (25OHD) levels (-0.43 SD of standardized natural log-transformed 25OHD per A allele; p value = 1.5 × 10-88). The effect on 25OHD was four times larger and independent of the effect of a previously described common variant near CYP2R1. By analyzing 8,711 individuals, we showed that heterozygote carriers of this low-frequency variant have an increased risk of vitamin D insufficiency (odds ratio [OR] = 2.2, 95% confidence interval [CI] = 1.78-2.78, p = 1.26 × 10-12). Individuals carrying one copy of this variant also had increased odds of multiple sclerosis (OR = 1.4, 95% CI = 1.19-1.64, p = 2.63 × 10-5) in a sample of 5,927 case and 5,599 control subjects. In conclusion, we describe a low-frequency CYP2R1 coding variant that exerts the largest effect upon 25OHD levels identified to date in the general European population and implicates vitamin D in the etiology of multiple sclerosis.
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Affiliation(s)
- Despoina Manousaki
- Department of Human Genetics, McGill University, Montreal, QC H3A 1B1, Canada; Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montreal, QC H3T 1E2, Canada
| | - Tom Dudding
- Medical Research Council Integrative Epidemiology Unit, University of Bristol, Bristol BS8 2BN, UK
| | - Simon Haworth
- Medical Research Council Integrative Epidemiology Unit, University of Bristol, Bristol BS8 2BN, UK
| | - Yi-Hsiang Hsu
- Institute for Aging Research, Hebrew SeniorLife, Boston, MA 02131, USA; Harvard Medical School, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Boston, MA 02142, USA
| | - Ching-Ti Liu
- Department of Biostatistics, Boston University School of Public Health, Boston, MA 02118, USA
| | - Carolina Medina-Gómez
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands; Generation R Study Group, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands
| | - Trudy Voortman
- Generation R Study Group, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands
| | - Nathalie van der Velde
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands; Section of Geriatrics, Department of Internal Medicine, Academic Medical Center, Amsterdam 1105 AZ, the Netherlands
| | - Håkan Melhus
- Department of Medical Sciences, Uppsala University, Uppsala 751 85, Sweden
| | - Cassianne Robinson-Cohen
- Kidney Research Institute, Division of Nephrology, University of Washington, Seattle, WA 98195, USA
| | - Diana L Cousminer
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Maria Nethander
- Centre for Bone and Arthritis Research, Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg 40530, Sweden; Bioinformatics Core Facility, Sahlgrenska Academy, University of Gothenburg, Gothenburg 41390, Sweden
| | - Liesbeth Vandenput
- Centre for Bone and Arthritis Research, Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg 40530, Sweden
| | - Raymond Noordam
- Section of Gerontology and Geriatrics, Department of Internal Medicine, Leiden University Medical Center, Leiden 2333 ZA, the Netherlands
| | - Vincenzo Forgetta
- Department of Human Genetics, McGill University, Montreal, QC H3A 1B1, Canada; Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montreal, QC H3T 1E2, Canada
| | - Celia M T Greenwood
- Department of Human Genetics, McGill University, Montreal, QC H3A 1B1, Canada; Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montreal, QC H3T 1E2, Canada; Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, QC H3A 1A2, Canada; Department of Oncology, McGill University, Montreal, QC H4A 3T2, Canada
| | - Mary L Biggs
- Cardiovascular Health Research Unit, Departments of Medicine and Biostatistics, University of Washington, Seattle, WA 98101, USA
| | - Bruce M Psaty
- Cardiovascular Health Research Unit, Departments of Medicine, Epidemiology, and Health Services, University of Washington, Seattle, WA 98101, USA; Kaiser Permanente Washington Health Research Unit, Seattle, WA 98101, USA
| | - Jerome I Rotter
- Institute for Translational Genomics and Population Sciences, Los Angeles Biomedical Research Institute, Torrance, CA 90502, USA; Department of Pediatrics, Harbor-UCLA Medical Center, Torrance, CA 90502, USA
| | - Babette S Zemel
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Division of Gastroenterology, Hepatology, and Nutrition, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Jonathan A Mitchell
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Division of Gastroenterology, Hepatology, and Nutrition, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Bruce Taylor
- Menzies Institute for Medical Research University of Tasmania, Locked Bag 23, Hobart, Tasmania 7000, Australia
| | - Mattias Lorentzon
- Centre for Bone and Arthritis Research, Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg 40530, Sweden; Geriatric Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, 43180 Mölndal, Sweden; Geriatric Medicine, Sahlgrenska University Hospital, 43180 Mölndal, Sweden
| | - Magnus Karlsson
- Clinical and Molecular Osteoporosis Research Unit, Department of Clinical Sciences, Lund University, 22241 Malmö, Sweden; Department of Orthopaedics, Skåne University Hospital, 22241 Malmö, Sweden
| | - Vincent V W Jaddoe
- Generation R Study Group, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands
| | - Henning Tiemeier
- Generation R Study Group, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands; Department of Child and Adolescent Psychiatry/Psychology, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands
| | - Natalia Campos-Obando
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands
| | - Oscar H Franco
- Department of Epidemiology, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands
| | - Andre G Utterlinden
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands; Generation R Study Group, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands
| | - Linda Broer
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands
| | - Natasja M van Schoor
- Department of Epidemiology and Biostatistics and EMGO Institute of Health and Care Research, VU University Medical Center, Amsterdam 1081 HV, the Netherlands
| | - Annelies C Ham
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands
| | - M Arfan Ikram
- Department of Epidemiology, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands; Department of Radiology and Nuclear Medicine, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands
| | - David Karasik
- Institute for Aging Research, Hebrew SeniorLife, Boston, MA 02131, USA
| | - Renée de Mutsert
- Department of Clinical Epidemiology, Leiden University Medical Center, Leiden 2333 ZA, the Netherlands
| | - Frits R Rosendaal
- Department of Clinical Epidemiology, Leiden University Medical Center, Leiden 2333 ZA, the Netherlands
| | - Martin den Heijer
- Department of Endocrinology, VU University Medical Center, Amsterdam 1081 HV, the Netherlands
| | - Thomas J Wang
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Lars Lind
- Department of Medical Sciences, Uppsala University, Uppsala 751 85, Sweden
| | - Eric S Orwoll
- Bone and Mineral Unit, Oregon Health & Science University, Portland, OR 97239, USA; Department of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
| | - Dennis O Mook-Kanamori
- Department of Clinical Epidemiology, Leiden University Medical Center, Leiden 2333 ZA, the Netherlands; Department of Public Health and Primary Care, Leiden University Medical Center, Leiden 2333 ZA, the Netherlands
| | - Karl Michaëlsson
- Department of Surgical Sciences, Uppsala University, 75105 Uppsala, Sweden
| | - Bryan Kestenbaum
- Kidney Research Institute, Division of Nephrology, University of Washington, Seattle, WA 98195, USA
| | - Claes Ohlsson
- Centre for Bone and Arthritis Research, Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg 40530, Sweden
| | - Dan Mellström
- Centre for Bone and Arthritis Research, Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg 40530, Sweden; Geriatric Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, 43180 Mölndal, Sweden
| | | | - Struan F A Grant
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Division of Endocrinology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Douglas P Kiel
- Institute for Aging Research, Hebrew SeniorLife, Boston, MA 02131, USA; Harvard Medical School, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Boston, MA 02142, USA; Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - M Carola Zillikens
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands
| | - Fernando Rivadeneira
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands; Generation R Study Group, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam 3015 GE, the Netherlands
| | - Stephen Sawcer
- Department of Clinical Neurosciences, University of Cambridge, Box 165, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0QQ, UK
| | - Nicholas J Timpson
- Medical Research Council Integrative Epidemiology Unit, University of Bristol, Bristol BS8 2BN, UK
| | - J Brent Richards
- Department of Human Genetics, McGill University, Montreal, QC H3A 1B1, Canada; Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montreal, QC H3T 1E2, Canada; Department of Twin Research and Genetic Epidemiology, King's College London, London WC2R 2LS, UK; Department of Medicine, McGill University, Montreal, QC H3G 1Y6, Canada.
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19
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Miller WL. Genetic disorders of Vitamin D biosynthesis and degradation. J Steroid Biochem Mol Biol 2017; 165:101-108. [PMID: 27060335 DOI: 10.1016/j.jsbmb.2016.04.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 04/03/2016] [Accepted: 04/05/2016] [Indexed: 01/10/2023]
Abstract
Vitamin D, an inactive secosteroid pro-hormone, is produced by the action of ultraviolet light on 7-dehydrocholesterol in the skin. The active hormone, 1,25(OH)2D is produced by sequential 25-hydroxylation in the liver, principally by CYP2R1, and 1α-hydroxylation in the kidney by CYP27B1. Mutations in CYP27B1 cause 1α-hydroxylase deficiency, also known as vitamin D dependent rickets type I or hereditary pseudo-vitamin D deficient rickets; very rare mutations in CYP2R1 can cause 25-hydroxylase deficiency. Both deficiencies cause hypocalcemia, secondary hyperparathyroidism, severe rickets in infancy, and low serum concentrations of 1,25(OH)2D; both disorders respond to hormonal replacement therapy with calcitriol. The inactivation of vitamin D is principally initiated by its 23- and 24-hydroxylation by CYP24A1. Mutations in CYP24A1 can cause both severe neonatal hypercalcemia and a less severe adult hypercalcemic syndrome. Other pathways of vitamin D metabolism are under investigation, notably its 20-hydroxylation by the cholesterol side-chain cleavage enzyme, CYP11A1.
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Affiliation(s)
- Walter L Miller
- Center for Reproductive Sciences and Department of Pediatrics, HSE 1634, University of California San Francisco, San Francisco, CA 94143-0556, USA.
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20
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Khokhar A, Castells S, Perez-Colon S. Genetic Disorders of Vitamin D Metabolism: Case Series and Literature Review. Clin Pediatr (Phila) 2016; 55:404-14. [PMID: 26701718 DOI: 10.1177/0009922815623231] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Aditi Khokhar
- SUNY Downstate Medical Center, Brooklyn, NY, USA Kings County Hospital Center, Brooklyn, NY, USA
| | | | - Sheila Perez-Colon
- SUNY Downstate Medical Center, Brooklyn, NY, USA Kings County Hospital Center, Brooklyn, NY, USA
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21
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Christakos S, Dhawan P, Verstuyf A, Verlinden L, Carmeliet G. Vitamin D: Metabolism, Molecular Mechanism of Action, and Pleiotropic Effects. Physiol Rev 2016; 96:365-408. [PMID: 26681795 PMCID: PMC4839493 DOI: 10.1152/physrev.00014.2015] [Citation(s) in RCA: 1037] [Impact Index Per Article: 129.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
1,25-Dihydroxvitamin D3 [1,25(OH)2D3] is the hormonally active form of vitamin D. The genomic mechanism of 1,25(OH)2D3 action involves the direct binding of the 1,25(OH)2D3 activated vitamin D receptor/retinoic X receptor (VDR/RXR) heterodimeric complex to specific DNA sequences. Numerous VDR co-regulatory proteins have been identified, and genome-wide studies have shown that the actions of 1,25(OH)2D3 involve regulation of gene activity at a range of locations many kilobases from the transcription start site. The structure of the liganded VDR/RXR complex was recently characterized using cryoelectron microscopy, X-ray scattering, and hydrogen deuterium exchange. These recent technological advances will result in a more complete understanding of VDR coactivator interactions, thus facilitating cell and gene specific clinical applications. Although the identification of mechanisms mediating VDR-regulated transcription has been one focus of recent research in the field, other topics of fundamental importance include the identification and functional significance of proteins involved in the metabolism of vitamin D. CYP2R1 has been identified as the most important 25-hydroxylase, and a critical role for CYP24A1 in humans was noted in studies showing that inactivating mutations in CYP24A1 are a probable cause of idiopathic infantile hypercalcemia. In addition, studies using knockout and transgenic mice have provided new insight on the physiological role of vitamin D in classical target tissues as well as evidence of extraskeletal effects of 1,25(OH)2D3 including inhibition of cancer progression, effects on the cardiovascular system, and immunomodulatory effects in certain autoimmune diseases. Some of the mechanistic findings in mouse models have also been observed in humans. The identification of similar pathways in humans could lead to the development of new therapies to prevent and treat disease.
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Affiliation(s)
- Sylvia Christakos
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, New Jersey; and Laboratory of Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
| | - Puneet Dhawan
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, New Jersey; and Laboratory of Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
| | - Annemieke Verstuyf
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, New Jersey; and Laboratory of Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
| | - Lieve Verlinden
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, New Jersey; and Laboratory of Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
| | - Geert Carmeliet
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, New Jersey; and Laboratory of Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
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Thacher TD, Fischer PR, Singh RJ, Roizen J, Levine MA. CYP2R1 Mutations Impair Generation of 25-hydroxyvitamin D and Cause an Atypical Form of Vitamin D Deficiency. J Clin Endocrinol Metab 2015; 100:E1005-13. [PMID: 25942481 PMCID: PMC4490307 DOI: 10.1210/jc.2015-1746] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 05/01/2015] [Indexed: 12/14/2022]
Abstract
CONTEXT Production of the active vitamin D hormone 1,25-dihydroxyvitamin D requires hepatic 25-hydroxylation of vitamin D. The CYP2R1 gene encodes the principal vitamin D 25-hydroxylase in humans. OBJECTIVE This study aimed to determine the prevalence of CYP2R1 mutations in Nigerian children with familial rickets and vitamin D deficiency and assess the functional effect on 25-hydroxylase activity. DESIGN AND PARTICIPANTS We sequenced the CYP2R1 gene in subjects with sporadic rickets and affected subjects from families in which more than one member had rickets. MAIN OUTCOME MEASURES Function of mutant CYP2R1 genes as assessed in vivo by serum 25-hydroxyvitamin D values after administration of vitamin D and in vitro by analysis of mutant forms of the CYP2R1. RESULTS CYP2R1 sequences were normal in 27 children with sporadic rickets, but missense mutations were identified in affected members of 2 of 12 families, a previously identified L99P, and a novel K242N. In silico analyses predicted that both substitutions would have deleterious effects on the variant proteins, and in vitro studies showed that K242N and L99P had markedly reduced or complete loss of 25-hydroxylase activity, respectively. Heterozygous subjects were less affected than homozygous subjects, and oral administration of vitamin D led to significantly lower increases in serum 25-hydroxyvitamin D in heterozygous than in control subjects, whereas homozygous subjects showed negligible increases. CONCLUSION These studies confirm that CYP2R1 is the principal 25-hydroxylase in humans and demonstrate that CYP2R1 alleles have dosage-dependent effects on vitamin D homeostasis. CYP2R1 mutations cause a novel form of genetic vitamin D deficiency with semidominant inheritance.
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Affiliation(s)
- Tom D Thacher
- Department of Family Medicine (T.D.T.), Jos University Teaching Hospital, Jos, Nigeria 930241; Department of Family Medicine (T.D.T.), Department of Pediatric and Adolescent Medicine (P.R.F.), and Department of Laboratory Medicine and Pathology (R.J.S.), Mayo Clinic, Rochester, Minnesota 55905; and The Children's Hospital of Philadelphia and Department of Pediatrics (J.R., M.A.L.), University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104
| | - Philip R Fischer
- Department of Family Medicine (T.D.T.), Jos University Teaching Hospital, Jos, Nigeria 930241; Department of Family Medicine (T.D.T.), Department of Pediatric and Adolescent Medicine (P.R.F.), and Department of Laboratory Medicine and Pathology (R.J.S.), Mayo Clinic, Rochester, Minnesota 55905; and The Children's Hospital of Philadelphia and Department of Pediatrics (J.R., M.A.L.), University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104
| | - Ravinder J Singh
- Department of Family Medicine (T.D.T.), Jos University Teaching Hospital, Jos, Nigeria 930241; Department of Family Medicine (T.D.T.), Department of Pediatric and Adolescent Medicine (P.R.F.), and Department of Laboratory Medicine and Pathology (R.J.S.), Mayo Clinic, Rochester, Minnesota 55905; and The Children's Hospital of Philadelphia and Department of Pediatrics (J.R., M.A.L.), University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104
| | - Jeffrey Roizen
- Department of Family Medicine (T.D.T.), Jos University Teaching Hospital, Jos, Nigeria 930241; Department of Family Medicine (T.D.T.), Department of Pediatric and Adolescent Medicine (P.R.F.), and Department of Laboratory Medicine and Pathology (R.J.S.), Mayo Clinic, Rochester, Minnesota 55905; and The Children's Hospital of Philadelphia and Department of Pediatrics (J.R., M.A.L.), University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104
| | - Michael A Levine
- Department of Family Medicine (T.D.T.), Jos University Teaching Hospital, Jos, Nigeria 930241; Department of Family Medicine (T.D.T.), Department of Pediatric and Adolescent Medicine (P.R.F.), and Department of Laboratory Medicine and Pathology (R.J.S.), Mayo Clinic, Rochester, Minnesota 55905; and The Children's Hospital of Philadelphia and Department of Pediatrics (J.R., M.A.L.), University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104
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23
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Marcucci G, Cianferotti L, Beck-Peccoz P, Capezzone M, Cetani F, Colao A, Davì MV, degli Uberti E, Del Prato S, Elisei R, Faggiano A, Ferone D, Foresta C, Fugazzola L, Ghigo E, Giacchetti G, Giorgino F, Lenzi A, Malandrino P, Mannelli M, Marcocci C, Masi L, Pacini F, Opocher G, Radicioni A, Tonacchera M, Vigneri R, Zatelli MC, Brandi ML. Rare diseases in clinical endocrinology: a taxonomic classification system. J Endocrinol Invest 2015; 38:193-259. [PMID: 25376364 DOI: 10.1007/s40618-014-0202-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 10/17/2014] [Indexed: 02/05/2023]
Abstract
PURPOSE Rare endocrine-metabolic diseases (REMD) represent an important area in the field of medicine and pharmacology. The rare diseases of interest to endocrinologists involve all fields of endocrinology, including rare diseases of the pituitary, thyroid and adrenal glands, paraganglia, ovary and testis, disorders of bone and mineral metabolism, energy and lipid metabolism, water metabolism, and syndromes with possible involvement of multiple endocrine glands, and neuroendocrine tumors. Taking advantage of the constitution of a study group on REMD within the Italian Society of Endocrinology, consisting of basic and clinical scientists, a document on the taxonomy of REMD has been produced. METHODS AND RESULTS This document has been designed to include mainly REMD manifesting or persisting into adulthood. The taxonomy of REMD of the adult comprises a total of 166 main disorders, 338 including all variants and subtypes, described into 11 tables. CONCLUSIONS This report provides a complete taxonomy to classify REMD of the adult. In the future, the creation of registries of rare endocrine diseases to collect data on cohorts of patients and the development of common and standardized diagnostic and therapeutic pathways for each rare endocrine disease is advisable. This will help planning and performing intervention studies in larger groups of patients to prove the efficacy, effectiveness, and safety of a specific treatment.
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Affiliation(s)
- G Marcucci
- Head, Bone Metablic Diseases Unit, Department of Surgery and Translational Medicine, University of Florence, Viale Pieraccini 6, 50139, Florence, Italy.
| | - L Cianferotti
- Head, Bone Metablic Diseases Unit, Department of Surgery and Translational Medicine, University of Florence, Viale Pieraccini 6, 50139, Florence, Italy
| | - P Beck-Peccoz
- Department of Clinical Sciences and Community Health, University of Milan and Endocrine Unit, Fondazione IRCCS Ca' Granda, Milan, Italy
| | - M Capezzone
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Endocrinology and Metabolism and Biochemistry, University of Siena, Policlinico Santa Maria alle Scotte, Siena, Italy
| | - F Cetani
- Unit of Endocrinology, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - A Colao
- Dipartimento di Medicina Clinica e Chirurgia, Università Federico II di Napoli, Naples, Italy
| | - M V Davì
- Section D, Department of Medicine, Clinic of Internal Medicine, University of Verona, Verona, Italy
| | - E degli Uberti
- Section of Endocrinology, Department of Medical Sciences, University of Ferrara, Ferrara, Italy
| | - S Del Prato
- Section of Metabolic Diseases and Diabetes, Department of Endocrinology and Metabolism, University of Pisa, Pisa, Italy
| | - R Elisei
- Unit of Endocrinology, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - A Faggiano
- Dipartimento di Medicina Clinica e Chirurgia, Università Federico II di Napoli, Naples, Italy
| | - D Ferone
- Endocrinology, Department of Internal Medicine and Medical Specialties and Center of Excellence for Biomedical Research, IRCCS AOU San Martino-IST, University of Genoa, Genoa, Italy
| | - C Foresta
- Department of Medicine and Centre for Human Reproduction Pathology, University of Padova, Padua, Italy
| | - L Fugazzola
- Department of Clinical Sciences and Community Health, University of Milan and Endocrine Unit, Fondazione IRCCS Ca' Granda, Milan, Italy
| | - E Ghigo
- Division of Endocrinology, Diabetology and Metabolism Department of Medical Sciences, University Hospital Città Salute e Scienza, Turin, Italy
| | - G Giacchetti
- Division of Endocrinology, Azienda Ospedaliero-Universitaria, Ospedali Riuniti Umberto I-GM Lancisi-G Salesi, Università Politecnica delle Marche, Ancona, Italy
| | - F Giorgino
- Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - A Lenzi
- Chair of Endocrinology, Section Medical Pathophysiology, Food Science and Endocrinology, Department Exp. Medicine, Sapienza University of Rome, Policlinico Umberto I, Rome, Italy
| | - P Malandrino
- Endocrinology, Department of Clinical and Molecular Biomedicine, Garibaldi-Nesima Medical Center, University of Catania, Catania, Italy
| | - M Mannelli
- Endocrinology Unit, Department of Experimental and Clinical Biomedical Sciences, University of Florence, Florence, Italy
| | - C Marcocci
- Department of Endocrinology and Metabolism, University of Pisa, Pisa, Italy
| | - L Masi
- Department of Orthopedic, Metabolic Bone Diseases Unit AOUC-Careggi Hospital, Largo Palagi, 1, Florence, Italy
| | - F Pacini
- Section of Endocrinology and Metabolism, University of Siena, Siena, Italy
| | - G Opocher
- Familial Cancer Clinic and Oncoendocrinology, Veneto Institute of Oncology, IRCCS, Padua, Italy
- Department of Medicine DIMED, University of Padova, Padova, Italy
| | - A Radicioni
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - M Tonacchera
- Unit of Endocrinology, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - R Vigneri
- Department of Clinical and Molecular Biomedicine, University of Catania, and Humanitas Catania Center of Oncology, Catania, Italy
| | - M C Zatelli
- Section of Endocrinology, Department of Medical Sciences, University of Ferrara, Ferrara, Italy
| | - M L Brandi
- Head, Bone Metablic Diseases Unit, Department of Surgery and Translational Medicine, University of Florence, Viale Pieraccini 6, 50139, Florence, Italy.
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Jehan F, Voloc A. [Classical actions of vitamin D: insights from human genetics and from mouse models on calcium and phosphate homeostasis]. Biol Aujourdhui 2014; 208:45-53. [PMID: 24948018 DOI: 10.1051/jbio/2014009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Indexed: 12/26/2022]
Abstract
At the beginning of the 20th century, the discovery of vitamin D by Sir EV McCollum allowed a better comprehension of its origin and its role, and made it possible to cure rickets, a largely prevalent disease at that time. The main role of vitamin D3 is to maintain calcium and phosphate homeostasis through the action of 1,25-dihydroxyvitamin D3, its active form. This underlies physiological functions related to calcium and phosphate, such as bone mineralization or muscle function. Progress in basic research for the last 40 years led to the discovery of the main hydroxylation steps that produce and catabolize the active form of vitamin D. It also uncovered the molecular aspects of vitamin D action, from its nuclear receptor, VDR, to the various target genes of this hormone. Recent progress in human genetics pointed out mutations in genes involved in vitamin D metabolism and 1,25-dihydroxyvitamin D3 actions. It also helped to understand the role of the major actors that control vitamin D production and effects, through 1,25-dihydroxyvitamin D3 actions on phosphate and calcium homeostasis, and on bone biology. Genetical engineering targeting the whole animal or defined tissues or cell types have yielded many mouse models in the past decades. When targeted to tissues important for vitamin D metabolism and activity, these models allowed a more detailed comprehension of vitamin effects on calcium and phosphorus homeostasis.
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Affiliation(s)
- Frédéric Jehan
- INSERM U1132, Hôpital Lariboisière, 75010 Paris, France - Université Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France
| | - Alexandru Voloc
- Université de Médecine et de Pharmacie "Nicolae Testemitanu", Chisinau, Moldavie
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25
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CYP2R1 is a major, but not exclusive, contributor to 25-hydroxyvitamin D production in vivo. Proc Natl Acad Sci U S A 2013; 110:15650-5. [PMID: 24019477 DOI: 10.1073/pnas.1315006110] [Citation(s) in RCA: 190] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Bioactivation of vitamin D consists of two sequential hydroxylation steps to produce 1α,25-dihydroxyvitamin D3. It is clear that the second or 1α-hydroxylation step is carried out by a single enzyme, 25-hydroxyvitamin D 1α-hydroxylase CYP27B1. However, it is not certain what enzyme or enzymes are responsible for the initial 25-hydroxylation. An excellent case has been made for vitamin D 25-hydroxylase CYP2R1, but this hypothesis has not yet been tested. We have now produced Cyp2r1 (-/-) mice. These mice had greater than 50% reduction in serum 25-hydroxyvitamin D3. Curiously, the 1α,25-dihydroxyvitamin D3 level in the serum remained unchanged. These mice presented no health issues. A double knockout of Cyp2r1 and Cyp27a1 maintained a similar circulating level of 25-hydroxyvitamin D3 and 1α,25-dihydroxyvitamin D3. Our results support the idea that the CYP2R1 is the major enzyme responsible for 25-hydroxylation of vitamin D, but clearly a second, as-yet unknown, enzyme is another contributor to this important step in vitamin D activation.
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26
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Zhang Z, He JW, Fu WZ, Zhang CQ, Zhang ZL. An analysis of the association between the vitamin D pathway and serum 25-hydroxyvitamin D levels in a healthy Chinese population. J Bone Miner Res 2013; 28:1784-92. [PMID: 23505139 DOI: 10.1002/jbmr.1926] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 02/19/2013] [Accepted: 03/04/2013] [Indexed: 12/31/2022]
Abstract
Vitamin D deficiency has been recognized as a major public health issue worldwide. Recent studies have indicated that genetic factors might play an important role in determining serum 25-hydroxyvitamin D [25(OH)D] levels in Caucasians and African Americans. However, the genes that contribute to the variation in serum 25(OH)D levels in Chinese are unknown. In this study, we screened 15 key genes within the vitamin D metabolic pathway using 96 single-nucleotide polymorphism (SNP) markers in a group of 2897 unrelated healthy Chinese subjects. Significant confounding factors that may influence the variability in serum 25(OH)D levels were used as covariates for association analyses. An association test for quantitative traits was performed to evaluate the association between candidate genes and serum 25(OH)D levels. In the present study, variants and/or haplotypes in GC, CYP2R1, and DHCR7/NADSYN1 were identified as being associated with 25(OH)D levels. Participants with three or four risk alleles of the two variants (GC-rs4588 and CYP2R1-rs10766197) had an increased chance of presenting with a 25(OH)D concentration lower than 20 ng/mL (odds ratio 2.121, 95% confidence interval 1.586-2.836, p = 6.1 × 10(-8) ) compared with those lacking the risk alleles. Each additional copy of a risk allele was significantly associated with a 0.12-fold decrease in the log-25(OH)D concentration (p = 3.7 × 10(-12) ). Haplotype TGA of GC rs705117-rs2282679-rs1491710, haplotype GAGTAC of GC rs842999-rs705120-rs222040-rs4588-rs7041-rs10488854, haplotype CA of GC rs1155563-rs222029, and haplotype AAGA of CYP2R1 rs7936142-rs12794714-rs2060793-rs16930609 were genetic risk factors toward a lower 25(OH)D concentration. In contrast, haplotype TGGGCCC of DHCR7/NADSYN1 rs1790349-rs7122671-rs1790329-rs11606033-rs2276360-rs1629220-rs2282618 were genetic protective factors. The results suggest that the GC, CYP2R1, and DHCR7/NADSYN1 genes might contribute to variability in the serum 25(OH)D levels in a healthy Chinese population in Shanghai. These markers could be used as tools in Mendelian randomization analyses of vitamin D, and they could potentially be drug targets in the Chinese population in Shanghai.
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Affiliation(s)
- Zeng Zhang
- Department of Orthopedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, People's Republic of China
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27
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Abstract
The vitamin D signal transduction system involves a series of cytochrome P450-containing sterol hydroxylases to generate and degrade the active hormone, 1α,25-dihydroxyvitamin D3, which serves as a ligand for the vitamin D receptor-mediated transcriptional gene expression described in companion articles in this review series. This review updates our current knowledge of the specific anabolic cytochrome P450s involved in 25- and 1α-hydroxylation, as well as the catabolic cytochrome P450 involved in 24- and 23-hydroxylation steps, which are believed to initiate inactivation of the vitamin D molecule. We focus on the biochemical properties of these enzymes; key residues in their active sites derived from crystal structures and mutagenesis studies; the physiological roles of these enzymes as determined by animal knockout studies and human genetic diseases; and the regulation of these different cytochrome P450s by extracellular ions and peptide modulators. We highlight the importance of these cytochrome P450s in the pathogenesis of kidney disease, metabolic bone disease, and hyperproliferative diseases, such as psoriasis and cancer; as well as explore potential future developments in the field.
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Affiliation(s)
- Glenville Jones
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
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28
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Al Mutair AN, Nasrat GH, Russell DW. Mutation of the CYP2R1 vitamin D 25-hydroxylase in a Saudi Arabian family with severe vitamin D deficiency. J Clin Endocrinol Metab 2012; 97:E2022-5. [PMID: 22855339 PMCID: PMC3462929 DOI: 10.1210/jc.2012-1340] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Inherited forms of vitamin D deficiency are rare causes of rickets and to date have been traced to mutations in three genes, VDR, encoding the 1α,25-dihydroxyvitamin D receptor, CYP27B1, encoding the vitamin D 1α-hydroxylase, and CYP2R1, encoding a microsomal vitamin D 25-hydroxylase. RESULTS Multiple mutations have been identified in VDR and CYP27B1 in patients with rickets, and thus, the roles of these two genes in vitamin D metabolism are unassailable. The case is less clear for CYP2R1, in which only a single mutation, L99P in exon 2 of the gene, has been identified in Nigerian families, and because multiple enzymes with vitamin D 25-hydroxylase activity have been identified. Here we report molecular genetic studies on two siblings from a Saudi family who presented with classic symptoms of vitamin D deficiency. The affected offspring inherited two different CYP2R1 mutations (367+1, G→A; 768, iT), which are predicted to specify null alleles. CONCLUSION We conclude that CYP2R1 is a major vitamin D 25-hydroxylase that plays a fundamental role in activation of this essential vitamin.
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Affiliation(s)
- Angham N Al Mutair
- Department of Pediatrics, Endocrinology Division, King Abdulaziz Medical City-Riyadh, College of Medicine, King Saud bin Abdulaziz University for Health Sciences and King Abdullah International Medical Research Center, Riyadh 11155, Kingdom of Saudi Arabia.
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29
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Zhu J, DeLuca HF. Vitamin D 25-hydroxylase – Four decades of searching, are we there yet? Arch Biochem Biophys 2012; 523:30-6. [DOI: 10.1016/j.abb.2012.01.013] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 01/21/2012] [Indexed: 11/16/2022]
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Abstract
Rickets is disorder of a growing child arising from disorders that result in impaired apoptosis of hypertrophic cells and mineralization of the growth plate. Rickets due to nutritional causes remains an important global problem. The factors responsible for resurgence of rickets among dark-skinned infants living in developed countries include the following: residence in northern or southern latitudes, voluntary avoidance of exposure to solar ultraviolet B radiation, maternal vitamin D deficiency during pregnancy, and prolonged breastfeeding without provision of vitamin D supplements. Fibroblast growth factor 23 (FGF23), secreted by osteocytes, is an important regulator of serum phosphate and 1,25(OH)(2)D(3) levels. Hypophosphatemic rickets resulting from increased synthesis or under-catabolism of FGF23 is reviewed.
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Affiliation(s)
- M Zulf Mughal
- Department of Paediatric Endocrinology, Royal Manchester Children's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Oxford Road, Manchester, M13 9WL, UK.
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31
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Ramasamy I. Inherited disorders of calcium homeostasis. Clin Chim Acta 2008; 394:22-41. [PMID: 18474231 DOI: 10.1016/j.cca.2008.04.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Revised: 03/30/2008] [Accepted: 04/14/2008] [Indexed: 12/19/2022]
Abstract
In mammals a complicated homeostatic mechanism has evolved to maintain near consistency of extracellular calcium ion levels. The homeostatic mechanism involves several hormones, which comprise among others, parathyroid hormone and vitamin D. The recent resurge in vitamin D deficiency, as a global health issue, has increased interest in the hormone. In addition to vitamin D deficiency, other causes of rickets are calcium deficiency and inherited disorders of vitamin D and phosphorus metabolism. Vitamin D-resistant syndromes are caused by hereditary defects in metabolic activation of the hormone or by mutations in the vitamin D receptor, which binds the hormone with high affinity and regulates the expression of genes through zinc finger mediated DNA binding and protein-protein interaction. Current interest is to correlate the type/position of mutations that result in disorders of vitamin D metabolism or in vitamin D receptor function with the variable phenotypic features and clinical presentation. The calcium sensing receptor plays a key role in calcium homeostasis. Loss of function mutations in the calcium sensing receptor can cause familial benign hypocalciuric hypercalcemia in heterozygotes and neonatal severe hyperparathyroidism when homozygous mutations occur in the calcium sensing receptor. Gain of function mutation can cause the opposite effect causing autosomal dominant hypocalcemia. Mouse models using targeted gene disruption strategies have been valuable tools to study the effect of mutations on the calcium sensing receptor or in the vitamin D activation pathway. Dysfunctional calcium sensing receptors with function altering mutations may be responsive to treatment with allosteric modulators of the calcium sensing receptor. Vitamin D analogs which induce unusual structural conformations on the vitamin D receptor may have a variety of therapeutic indications. This review summarises recent advances in knowledge of the molecular pathology of inherited disorders of calcium homeostasis.
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Affiliation(s)
- Indra Ramasamy
- Department of Chemical Pathology, Dumfries and Galloway District Hospital, Bankend Road, Dumfries, UK.
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32
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Saadi HF, Nagelkerke N, Benedict S, Qazaq HS, Zilahi E, Mohamadiyeh MK, Al-Suhaili AI. Predictors and relationships of serum 25 hydroxyvitamin D concentration with bone turnover markers, bone mineral density, and vitamin D receptor genotype in Emirati women. Bone 2006; 39:1136-1143. [PMID: 16814623 DOI: 10.1016/j.bone.2006.05.010] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2005] [Revised: 05/07/2006] [Accepted: 05/11/2006] [Indexed: 11/19/2022]
Abstract
OBJECTIVES To determine factors influencing serum 25 hydroxyvitamin D (25OHD) concentration and relationships between serum 25OHD concentration, bone turnover markers, bone mineral density (BMD), and vitamin D receptor (VDR) genotype in Emirati women. METHODS Serum 25OHD, parathyroid hormone (PTH), osteocalcin (OC), vitamin D binding protein (VDBP), and urinary deoxypyrdinoline (UDPD) concentrations and VDR genotype were determined in Emirati women volunteers who were participating in a study aiming at establishing a reference database for BMD. RESULTS Serum 25OHD concentration in the 259 women volunteers was 25.3 +/- 10.8 nmol/l (mean +/- SD), and all had vitamin D deficiency (25OHD <80 nmol/l). Mean serum 25OHD was highest in April (29.2 +/- 13.0 nmol/l), which marks the end of the short and cooler winter season, and lowest in August (18.2 +/- 5.9 nmol/l). No significant difference in 25OHD concentration was noted among Emirati women wearing different dress styles, but the mean serum 25OHD was significantly lower in comparison with non-Arab Caucasian women volunteers who dressed in a Western style (P < 0.001). Serum 25OHD correlated positively with age (r = 0.2), number of pregnancies (r = 0.16), dietary vitamin D intake (r = 0.15), serum calcium (r = 0.14), phosphorus (r = 0.14), VDBP (r = 0.15), and urinary calcium/creatinine (r = 0.2), and inversely with PTH (r = -0.22), OC (r = -0.13), and UDPD/creatinine (r = -0.15); P < 0.05 for all correlations. Multiple linear regression analysis showed that age, dietary vitamin D intake, multivitamin intake, and cooler season were independent positive predictors of serum 25OHD concentration (R(2) = 0.18). The frequencies of VDR genotypes were 36% GG, 44.1% AG, and 19.9% AA. Allele frequencies were 58% for G allele and 42% for A allele and were in Hardy-Weinberg equilibrium (x(2) = 1.44; P > 0.1). There was no statistically significant influence of VDR genotype on bone turnover or BMD. CONCLUSIONS Vitamin D deficiency is highly prevalent in Emirati women and appears largely attributable to insufficient sunlight exposure. It is associated with increased bone turnover. VDR genotype does not appear to influence bone turnover markers or BMD in Emirati women.
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Affiliation(s)
- Hussein F Saadi
- Department of Internal Medicine, Faculty of Medicine and Health Sciences, United Arab Emirates University, P O Box 17666, Al Ain, UAE.
| | - Nicolaas Nagelkerke
- Department of Community Medicine, Faculty of Medicine and Health Sciences, United Arab Emirates University, UAE
| | - Sheela Benedict
- Department of Internal Medicine, Faculty of Medicine and Health Sciences, United Arab Emirates University, P O Box 17666, Al Ain, UAE
| | - Hussein S Qazaq
- Department of Nutrition, Ministry of Health, Tawam Hospital, General Authority for Health Services for Abu Dhabi, Al Ain, UAE
| | - Erica Zilahi
- Department of Medical Microbiology, Faculty of Medicine and Health Sciences, United Arab Emirates University, UAE
| | - Mohammad K Mohamadiyeh
- Division of Nuclear Medicine, Tawam Hospital, General Authority for Health Services for Abu Dhabi, Al Ain, UAE
| | - Abdulrahim I Al-Suhaili
- Division of Nuclear Medicine, Tawam Hospital, General Authority for Health Services for Abu Dhabi, Al Ain, UAE
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Abstract
The epidemic scourge of rickets in the 19th century was caused by vitamin D deficiency due to inadequate sun exposure and resulted in growth retardation, muscle weakness, skeletal deformities, hypocalcemia, tetany, and seizures. The encouragement of sensible sun exposure and the fortification of milk with vitamin D resulted in almost complete eradication of the disease. Vitamin D (where D represents D2 or D3) is biologically inert and metabolized in the liver to 25-hydroxyvitamin D [25(OH)D], the major circulating form of vitamin D that is used to determine vitamin D status. 25(OH)D is activated in the kidneys to 1,25-dihydroxyvitamin D [1,25(OH)2D], which regulates calcium, phosphorus, and bone metabolism. Vitamin D deficiency has again become an epidemic in children, and rickets has become a global health issue. In addition to vitamin D deficiency, calcium deficiency and acquired and inherited disorders of vitamin D, calcium, and phosphorus metabolism cause rickets. This review summarizes the role of vitamin D in the prevention of rickets and its importance in the overall health and welfare of infants and children.
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Affiliation(s)
- Michael F Holick
- Department of Medicine, Section of Endocrinology, Nutrition, and Diabetes, and Vitamin D, Skin and Bone Research Laboratory, Boston University Medical Center, Boston, Massachusetts 02118, USA.
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Gupta RP, He YA, Patrick KS, Halpert JR, Bell NH. CYP3A4 is a vitamin D-24- and 25-hydroxylase: analysis of structure function by site-directed mutagenesis. J Clin Endocrinol Metab 2005; 90:1210-9. [PMID: 15546903 DOI: 10.1210/jc.2004-0966] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Studies were performed to identify the microsomal enzyme that 24-hydroxylates vitamin D, whether 25-hydroxylation occurs, and structure function of the enzyme. Sixteen hepatic recombinant microsomal cytochrome P450 enzymes expressed in baculovirus-infected insect cells were screened for 24-hydroxylase activity. CYP3A4, a vitamin D-25-hydroxylase, and CYP1A1 had the highest 24-hydroxylase activity with 1 alpha-hydroxyvitamin D(2) (1 alpha OHD(2)) as substrate. The ratio of rates of 24-hydroxylation of 1 alpha-hydroxyvitamin D(3) (1 alpha OHD(3)), 1 alpha OHD(2), and vitamin D(2) by CYP3A4 was 3.6/2.8/1.0. Structures of 24-hydroxyvitamin D(2), 1,24(S)-dihydroxyvitamin D(2), and 1,24-dihydroxyvitamin D(3) were confirmed by HPLC and gas chromatography retention time and mass spectroscopy. In characterized human liver microsomes, 24-hydroxylation of 1 alpha OHD(2) by CYP3A4 correlated significantly with 6 beta-hydroxylation of testosterone, a marker of CYP3A4 activity. 24-Hydroxylase activity in recombinant CYP3A4 and pooled human liver microsomes showed dose-dependent inhibition by ketoconazole, troleandomycin, alpha-naphthoflavone, and isoniazid, known inhibitors of CYP3A4. Rates of 24- and 25-hydroxylation of 1 alpha OHD(2) and 1 alpha OHD(3) were determined in recombinant wild-type CYP3A4 and site-directed mutants and naturally occurring variants expressed in Escherichia coli. Substitution of residues showed the most prominent alterations of function at residues 119, 120, 301, 305, and 479. Thus, CYP3A4 is both a 24- and 25-hydroxylase for vitamin D(2), 1 alpha OHD(2), and 1 alpha OHD(3).
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Affiliation(s)
- Ram P Gupta
- Department of Medicine, Medical University of South Carolina, P.O. Box 250775, Charleston, South Carolina 29425, USA
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Cheng JB, Levine MA, Bell NH, Mangelsdorf DJ, Russell DW. Genetic evidence that the human CYP2R1 enzyme is a key vitamin D 25-hydroxylase. Proc Natl Acad Sci U S A 2004; 101:7711-5. [PMID: 15128933 PMCID: PMC419671 DOI: 10.1073/pnas.0402490101] [Citation(s) in RCA: 457] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2004] [Indexed: 01/28/2023] Open
Abstract
The synthesis of bioactive vitamin D requires hydroxylation at the 1 alpha and 25 positions by cytochrome P450 enzymes in the kidney and liver, respectively. The mitochondrial enzyme CYP27B1 catalyzes 1 alpha-hydroxylation in the kidney but the identity of the hepatic 25-hydroxylase has remained unclear for >30 years. We previously identified the microsomal CYP2R1 protein as a potential candidate for the liver vitamin D 25-hydroxylase based on the enzyme's biochemical properties, conservation, and expression pattern. Here, we report a molecular analysis of a patient with low circulating levels of 25-hydroxyvitamin D and classic symptoms of vitamin D deficiency. This individual was found to be homozygous for a transition mutation in exon 2 of the CYP2R1 gene on chromosome 11p15.2. The inherited mutation caused the substitution of a proline for an evolutionarily conserved leucine at amino acid 99 in the CYP2R1 protein and eliminated vitamin D 25-hydroxylase enzyme activity. These data identify CYP2R1 as a biologically relevant vitamin D 25-hydroxylase and reveal the molecular basis of a human genetic disease, selective 25-hydroxyvitamin D deficiency.
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Affiliation(s)
- Jeffrey B Cheng
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
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Lin CJ, Dardis A, Wijesuriya SD, Abdullah MA, Casella SJ, Miller WL. Lack of mutations in CYP2D6 and CYP27 in patients with apparent deficiency of vitamin D 25-hydroxylase. Mol Genet Metab 2003; 80:469-72. [PMID: 14654361 DOI: 10.1016/j.ymgme.2003.10.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Activation of vitamin D requires hepatic 25-hydroxylation and renal 1alpha-hydroxylation. Defects in renal P450c1alpha are well-described, but few patients with defective vitamin D 25-hydroxylation are reported. The cytochrome P450 enzymes CYP2D6 and CYP27 are potential 25-hydroxylases. We sequenced both genes in two reported families with hepatic 25-hydroxylase deficiency and found no mutations. 25-Hydroxylation occurs in both mitochondria and microsomes. The existence genes encoding distinct enzymes would provide genetic redundancy, explaining the rarity of apparent vitamin D 25-hydroxylase deficiency.
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Affiliation(s)
- Chin Jia Lin
- Department of Pediatrics, University of California, San Francisco, CA 94143-0978, USA
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Abstract
The principal hormone regulator of bone mineralization is vitamin D, which must be activated by a metabolic pathway consisting of a 25-hydroxylase and a 1alpha-hydroxylase to yield 1,25 (OH)(2)D. The hormonal regulation of vitamin D activation is at the level of the 1alpha-hydroxylase. We review the biology of vitamin D, the biochemistry of its activation and the molecular biology of the vitamin D-metabolizing enzymes. Recent advances have resulted in the cloning of the human vitamin D 1alpha-hydroxylase and the identification of mutations in its gene that cause Vitamin D Dependent Rickets type I.
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Affiliation(s)
- W L Miller
- Department of Pediatrics and the Metabolic Research Unit, University of California, San Francisco, CA 94143-0978, USA
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Gascon-Barré M, Demers C, Ghrab O, Theodoropoulos C, Lapointe R, Jones G, Valiquette L, Ménard D. Expression of CYP27A, a gene encoding a vitamin D-25 hydroxylase in human liver and kidney. Clin Endocrinol (Oxf) 2001; 54:107-15. [PMID: 11167933 DOI: 10.1046/j.1365-2265.2001.01160.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Vitamin D3 (D3) is not active but must be hydroxylated at C-25 in liver before acquiring its hormonal potential in the kidney. The sterol-27 hydroxylase (gene symbol: CYP27A) catalyses the oxidation of sterol side chain in bile acid synthesis but the enzyme is also known as a D3-25 hydroxylase. The study examined the expression of the gene encoding CYP27A in adult and fetal human livers and kidneys. Thirty-nine adults (18 men and 21 women; mean age 58 years in men and 57 years in women) and three normal fetuses gestational age 17-19 weeks were studied. Tissue CYP27A mRNA and serum 25OHD concentrations were measured. Normal specimens: CYP27A transcript was found to be higher in adult than in fetal livers but its expression was similar in adult and fetal kidneys. In fetuses, no difference was observed between CYP27A levels in livers and kidneys. In adult livers CYP27A levels were higher in women than in men. Hepatic CYP27A mRNA and serum 25OHD concentrations were both found to be higher in summer than in winter. Multiple linear regression analyses indicate that the season of the year and the serum 25OHD concentrations (but not 1,25(OH)2D concentrations) are the best predictors of CYP27A mRNA abundance in normal adult livers. In situ hybridization illustrates a clear label in hepatocytes which increases in intensity in the perivenous region of the hepatic acinus. Pathological specimens: In one man with an hepatic carcinoma there was a very large increase in CYP27A (> 1000 fold) compared to the level found in the normal liver. In that patient, serum 25OHD concentrations were found to be high considering the level of CYP27A mRNA in the normal hepatic area suggesting that the neoplastic tissue contributed to the C-25 hydroxylation of vitamin D. Specimens obtained from two patients suffering from focal hepatic hyperplasia indicate that in one case the level of CYP27A mRNA was twice as high in the pathological than in the normal area while in the other its levels were similar in both areas. No difference in the CYP27A transcript was observed between specimens obtained from normal areas and those obtained form either an hepatic adenoma or from two intrahepatic colonic metastases. CYP27A is present not only in the human adult liver but also in the adult kidney, and in the fetal liver and kidney. Our findings illustrate that CYP27A can be significantly upregulated in certain pathological situations such as in hepatic carcinoma and that the neoplastic tissue could contribute to the circulating concentration of 25OHD.
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Affiliation(s)
- M Gascon-Barré
- Département de Pharmacologie, Faculté de médecine Université de Montréal, Québec, Canada.
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Abstract
The rate-limiting, hormonally regulated step in the bioactivation of vitamin D is renal 1 alpha-hydroxylation by P450c1 alpha. In late 1997, we reported the cloning of the human cDNA and gene from keratinocytes, and established that P450c1 alpha mutations cause vitamin D-dependent rickets, type I, while three other groups reported the cloning of the rodent enzyme. The genetics of P450c1 alpha are well established, with studies of over 30 patients, but the molecular mechanisms for the hormonal regulation of P450c1 alpha are still under investigation.
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Affiliation(s)
- W L Miller
- Department of Pediatrics, Building MR-IV, Room 209, University of California San Francisco, San Francisco, CA 94143-0978, USA.
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Abstract
The disorders of vitamin D metabolism are inherited metabolic abnormalities involving mutations of the vitamin D receptor or enzymes involved in the metabolism of vitamin D to its biologically active form 1,25-dihydroxyvitamin D. Although these mutations are rare, studies in affected patients and animal models have helped to identify critical actions of vitamin D and the mechanism by which it exerts its effects. Vitamin D deficiency, however, is an increasingly recognized problem among the elderly and in the general population. Screening for vitamin D deficiency only in those patients with known risk factors will result in a large proportion of unrecognized affected patients.
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Affiliation(s)
- M K Thomas
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
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Thacher TD, Fischer PR, Pettifor JM, Lawson JO, Isichei CO, Chan GM. Case-control study of factors associated with nutritional rickets in Nigerian children. J Pediatr 2000; 137:367-73. [PMID: 10969262 DOI: 10.1067/mpd.2000.107527] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Because the causes of nutritional rickets in tropical countries are poorly understood, we conducted a case-control study to determine factors associated with rickets in Nigerian children. STUDY DESIGN We compared 123 Nigerian children who had rickets with matched control subjects. Dietary, demographic, anthropometric, and biochemical data were collected to assess factors related to calcium and vitamin D status, which might predispose children to rickets. RESULTS Mean (+/- SD) daily dietary calcium intake was low in both children with rickets and control children (217 +/- 88 mg and 214 +/- 77 mg, respectively; P =.64). Children with rickets had a greater proportion of first-degree relatives with a history of rickets (14.6% vs 3.1%; P <.001), a shorter mean duration of breast-feeding (16.0 vs 17.3 months; P =.041), and a delayed age of walking (14 vs 12 months; P <.001). Among children with rickets, biochemical features suggestive of calcium deficiency included hypocalcemia, extremely low calcium excretion, and elevated 1, 25-dihydroxyvitamin D and parathyroid hormone values. Median 25-hydroxyvitamin D concentrations were 32 and 50 nmol/L (13 and 20 ng/mL) in children with rickets and control children, respectively (P <.0001). Only 46 subjects with rickets (37%) had 25-hydroxyvitamin D values <30 nmol/L (12 ng/mL). CONCLUSIONS Vitamin D deficiency appears unlikely to be the primary etiologic factor of rickets in African children. Moreover, low dietary calcium intake alone does not account for rickets. Insufficient dietary calcium probably interacts with genetic, hormonal, and other nutritional factors to cause rickets in susceptible children.
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Affiliation(s)
- T D Thacher
- Department of Family Medicine, Jos University Teaching Hospital, Jos, Nigeria
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Abstract
The genetic control of calcium, phosphorus, cartilage, and bone metabolism is discussed, and many of the genes involved in this process are described. Mutations in these genes that lead to the clinical disorders associated with hypercalcemia, hypocalcemia, rickets, and osteochondrodystrophies are delineated.
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Affiliation(s)
- A W Root
- Department of Pediatrics, University of South Florida College of Medicine, Tampa, USA
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Abstract
The principal hormonal regulator of bone mineralization is vitamin D, which must be activated by a metabolic pathway consisting of a 25-hydroxylase and a 1 alpha-hydroxylase to yield 1,25 dihydroxy vitamin D. The hormonal regulation of vitamin D activation is at the level of the 1 alpha-hydroxylase. This article reviews the biology of vitamin D, and describes the biochemistry of its activation and the molecular biology of the vitamin D-metabolizing enzymes. Recent advances, principally in the authors' laboratories, have resulted in the cloning of the human vitamin D 1 alpha-hydroxylase and the identification of mutations in its gene that cause Vitamin D Dependent Rickets type I.
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Affiliation(s)
- W L Miller
- Department of Pediatrics, University of California, San Francisco School of Medicine, USA
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Abstract
Dietary deficiency of vitamin D, genetic disorders of its bioactivation to 1,25-dihydroxyvitamin D [1,25(OH)2D], or disorders of vitamin D action can cause rickets. The rate-limiting, hormonally-regulated, biologically activating step in the synthesis of 1,25(OH)2D is the 1 alpha-hydroxylation of 25-hydroxyvitamin D, which occurs in kidney and other tissues and is mediated by a mitochondrial cytochrome P450 enzyme, P450c1 alpha. After many years of effort, the cDNA and gene for this enzyme were cloned in late 1997. Mutations in the P450c1 alpha gene, located on chromosome 12, cause 1 alpha-hydroxylase deficiency, also known as vitamin D-dependent rickets type I, an autosomal recessive disease characterized by rickets and impaired growth due to failure of renal synthesis of 1,25(OH)2D. X-linked hypophosphatemic rickets, a dominantly inherited disease, is caused by mutations in the PHEX gene, whose function in regulating renal phosphate and vitamin D metabolism remains to be elucidated.
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Affiliation(s)
- W L Miller
- Department of Pediatrics, University of California at San Francisco, Berkeley, USA
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Abstract
Osteomalacia is a generalized bone disorder characterized by impairment of mineralization, leading to accumulation of unmineralized matrix or osteoid in the skeleton. The classical clinical features of osteomalacia include musculoskeletal pain, skeletal deformity, muscle weakness and symptomatic hypocalcaemia. In childhood the features of osteomalacia are accompanied by rickets, with widening of the epiphyses and impaired skeletal growth. The major cause of osteomalacia is vitamin D deficiency, which is most often due to reduced cutaneous production of vitamin D in housebound elderly people, immigrants to Northern countries and women who adopt strict dress codes which prohibit exposure of uncovered skin. Vitamin D deficiency osteomalacia may also occur with malabsorption, liver disease and anticonvulsant therapy. Less commonly, osteomalacia may result from abnormal vitamin D metabolism, resistance to the action of vitamin D, hypophosphataemia or toxic effects on osteoblast function.
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Abstract
OBJECTIVES There are numerous laboratory investigations available for the assessment of an infant with suspected metabolic bone disease (MBD); thus, comprehensive laboratory investigations on every aspect of MBD would impose unnecessary stress to the infant and the costs involved would be prohibitive. An overview of the assessment of an infant with suspected MBD, in particular, nutrition-related bone disease, is presented. Our objectives include an understanding of: 1. the importance of appropriate information from history and physical examination to guide the laboratory investigations; 2. relevance and limitations of specific laboratory investigations: a. radiologic studies include diagnostic radiographs and quantitative bone mass determination by dual energy x-ray absorptiometry, b. biochemical measurements to determine mineral homeostasis and bone turnover, c. vitamin (vitamin D metabolites) and hormonal (parathyroid hormone and calcitonin) measurements; with respect to diagnosis and monitoring of the natural progress or response to therapy. CONCLUSION Relevant information from clinical history and physical examination, and an understanding of the role and limitations of various laboratory investigations, would allow the optimal utilization of laboratory tests in the assessment of an infant with MBD.
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Affiliation(s)
- W W Koo
- Department of Pediatrics, Wayne State University, Detroit, Michigan 48202, USA
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