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Kashyap J, Kumari N, Ponnusamy K, Tyagi RK. Hereditary Vitamin D-Resistant Rickets (HVDRR) associated SNP variants of vitamin D receptor exhibit malfunctioning at multiple levels. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2023; 1866:194891. [PMID: 36396100 DOI: 10.1016/j.bbagrm.2022.194891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 10/11/2022] [Accepted: 11/02/2022] [Indexed: 11/16/2022]
Abstract
Vitamin D receptor (VDR) is a member of the nuclear receptor superfamily. It is a primary regulator of calcium and phosphate homeostasis required for skeleton and bone mineralization. Vitamin D in active form 1α,25 dihydroxyvitamin-D3 mediates its cellular functions by binding to VDR. Active VDR forms heterodimers with partner RXR (retinoid X receptor) to execute its physiological actions. HVDRR (Hereditary Vitamin D-Resistant Rickets) is a rare genetic disorder that occurs because of generalized resistance to the 1α,25(OH)2D3. HVDRR is caused by the polymorphic variations in VDR gene leading to defective intestinal calcium absorption and mineralization of newly forming bones. Using point and deletion SNPs of VDR we have studied several HVDRR-associated SNP variants for their subcellular dynamics, transcriptional functions, 'genome bookmarking', heterodimeric interactions with RXR, and receptor stability. We previously reported that VDR is a 'mitotic bookmarking factor' that remains constitutively associated with the mitotic chromatin to inherit 'transcriptional memory', however the mechanistic details remained unclear. We document that 'genome bookmarking' property by VDR is critically impaired by naturally occurring HVDRR-associated point and deletion variants found in patients. Furthermore, these HVDRR-associated SNP variants of VDR were found to be compromised in transcriptional function, nuclear translocation, protein stability and intermolecular interactions with its heterodimeric partner RXR. Intriguingly, majority of these disease-allied functional defects failed to be rescued by RXR. Our findings suggest that the HVDRR-associated SNP variations influence the normal functioning of the receptor, and this derived understanding may help in the management of disease with precisely designed small molecule modulators.
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Affiliation(s)
- Jyoti Kashyap
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi 110067, India
| | - Neha Kumari
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi 110067, India
| | | | - Rakesh K Tyagi
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi 110067, India; Special Centre for Systems Medicine (Concurrent Faculty), Jawaharlal Nehru University, New Delhi 110067, India.
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Litaiem N, Chabchoub I, Bacha T, Slouma M, Zeglaoui F, Khachemoune A. Rickets in association with skin diseases and conditions: A review with emphasis on screening and prevention. PHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE 2020; 36:339-350. [PMID: 32645757 DOI: 10.1111/phpp.12590] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 06/01/2020] [Accepted: 07/05/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Rickets is a common disease worldwide. In the developed world, its prevalence dramatically decreased but still diagnosed in at-risk populations. The skin plays a critical role in vitamin D synthesis. Therefore, several skin diseases, especially keratinization disorders, could lead to impaired vitamin D metabolism and vitamin D deficient rickets. OBJECTIVE The article aimed to summarize the current knowledge of skin diseases and conditions associated with rickets. METHODS To examine the association between rickets and skin diseases, we performed a systematic review of the literature using PubMed database. The search included studies published from the database inception to August 2019. RESULTS A total number of 75 articles were included. Identified conditions associated with rickets were ichthyosis being a more common skin diseases, alopecia, epidermal and melanocytic nevi, xeroderma pigmentosum, mastocytosis, psoriasis, and atopic dermatitis. Three types of rickets were identified: vitamin D-dependent rickets, hypocalcemic vitamin D-dependent rickets type 2, and hypophosphatemic rickets. Cutaneous skeletal hypophosphatemia syndrome is a newly described and under-recognized condition. It is defined by the association of epidermal or melanocytic nevi, hypophosphatemic rickets, and elevated levels of fibroblast growth factor 23. Rickets in patients with ichthyosis was mainly due to impaired ability of ichthyotic skin to synthesize vitamin D, poor UV penetration of the skin caused by keratinocyte proliferation, and dark phototype. The latter may be considered a risk factor for rickets in patients with ichthyosis. CONCLUSION Despite its rarity, these associations should be properly recognized by dermatologists. Early diagnosis of rickets is important to prevent growth retardation and skeletal deformities.
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Affiliation(s)
- Noureddine Litaiem
- Department of Dermatology, Charles Nicolle Hospital, Tunis, Tunisia
- Faculty of Medicine of Tunis, University of Tunis el Manar, Tunis, Tunisia
| | - Ines Chabchoub
- Department of Dermatology, Charles Nicolle Hospital, Tunis, Tunisia
- Faculty of Medicine of Tunis, University of Tunis el Manar, Tunis, Tunisia
| | - Takwa Bacha
- Department of Dermatology, Charles Nicolle Hospital, Tunis, Tunisia
- Faculty of Medicine of Tunis, University of Tunis el Manar, Tunis, Tunisia
| | - Maroua Slouma
- Faculty of Medicine of Tunis, University of Tunis el Manar, Tunis, Tunisia
- Department of Rheumatology, Military Hospital, Tunis, Tunisia
| | - Faten Zeglaoui
- Department of Dermatology, Charles Nicolle Hospital, Tunis, Tunisia
- Department of Rheumatology, Military Hospital, Tunis, Tunisia
| | - Amor Khachemoune
- State University of New York Downstate and Veterans Affairs Medical Center, Brooklyn, NY, USA
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Functional Analysis of VDR Gene Mutation R343H in A Child with Vitamin D-Resistant Rickets with Alopecia. Sci Rep 2017; 7:15337. [PMID: 29127362 PMCID: PMC5681508 DOI: 10.1038/s41598-017-15692-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 11/01/2017] [Indexed: 11/09/2022] Open
Abstract
The functional study of different mutations on vitamin D receptor (VDR) gene causing hereditary vitamin D-resistant rickets (HVDRR) remains limited. This study was to determine the VDR mutation and the mechanisms of this mutation-causing phenotype in a family with HVDRR and alopecia. Phenotype was analyzed, and in vitro functional studies were performed. The proband and his affected sister exhibited typical HVDRR with alopecia, and their biochemical and radiographic abnormalities but not alopecia responded to supraphysiological doses of active vitamin D3. A novel homozygous missense R343H mutation in the exon 9 of VDR residing in the retinoid X receptor (RXR)-binding domain was identified. The expression level and C-terminal conformation of R343H mutant are not different from the wild-type VDR. This mutant had no effect on the nuclear localization of VDR, VDR-RXR heterodimerization, but it impaired CYP24A1 promoter activity in the presence of 1,25 (OH)2 vitamin D3, at least in part, mediated through specific nuclear receptor coactivator. Simulation models revealed the vanished interaction between guanidinium group of R343 and carboxyl group of E269. Without affecting the expression, conformation, nuclear location of VDR or heteridimerization with RXR, VDR-R343H impairs the transactivation activity of VDR on downstream transcription, accounting for HVDRR features with alopecia.
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Rochel N, Molnár F. Structural aspects of Vitamin D endocrinology. Mol Cell Endocrinol 2017; 453:22-35. [PMID: 28257826 DOI: 10.1016/j.mce.2017.02.046] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/27/2017] [Accepted: 02/27/2017] [Indexed: 12/12/2022]
Abstract
1α,25-Dihydroxvitamin D3 (1,25(OH)2D3) is the hormonally active form of vitamin D3. Its synthesis and its metabolites, their transport and elimination as well as action on transcriptional regulation involves the harmonic cooperation of diverse proteins with vitamin D binding capacities such as vitamin D binding protein (DBP), cytochrome P450 enzymes or the nuclear vitamin receptor (VDR). The genomic mechanism of 1,25(OH)2D3 action involves its binding to VDR that functionally acts as a heterodimer with retinoid X receptor. The crystal structures of the most important proteins for vitamin D3, VDR, DBP, CYP2R1 and CYP24A1, have provided identification of mechanisms of actions of these proteins and those mediating VDR-regulated transcription. This review will present the structural information on recognition of the vitamin D3 and metabolites by CYP proteins and DBP as well as the structural basis of VDR activation by 1,25(OH)2D3 and metabolites. Additionally, we will describe, the implications of the VDR mutants associated with hereditary vitamin D-resistant rickets (HVDRR) that display impaired function.
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Affiliation(s)
- Natacha Rochel
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Institut National de La Santé et de La Recherche Médicale (INSERM), U964/Centre National de Recherche Scientifique (CNRS), UMR7104/Université de Strasbourg, 67404 Illkirch, France.
| | - Ferdinand Molnár
- Institute of Biopharmacy, School of Pharmacy, Faculty of Heath Science, University of Eastern Finland, Yliopistonranta 1C, Canthia 2036, 70210 Kuopio, Finland.
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Ghazi AA, Zadeh-Vakili A, Zarif Yeganeh M, Alamdari S, Amouzegar A, Khorsandi AA, Amirbaigloo A, Azizi F. Hereditary Vitamin D Resistant Rickets: Clinical, Laboratory, and Genetic Characteristics of 2 Iranian Siblings. Int J Endocrinol Metab 2017; 15:e12384. [PMID: 29201067 PMCID: PMC5702004 DOI: 10.5812/ijem.12384] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 07/02/2017] [Indexed: 01/31/2023] Open
Abstract
PURPOSE AND METHODS Hereditary vitamin D resistant rickets (HVDRR) is a rare disease that presents with signs and symptoms of rickets, alopecia, and growth retardation during the early years of life. The disease is caused by mutations in the vitamin D receptor (VDR) gene, which leads to unresponsiveness of the mutant receptor to 1-25(OH) 2 D3. The disease is transmitted as an autosomal recessive disorder and is found with equal frequency in males and females. The disease is rarely encountered and only about 100 cases are reported so far. The current paper reported the clinical and laboratory characteristics of 2 Iranian siblings with this disorder. RESULTS AND CONCLUSION They presented with rickets, growth retardation, muscle weakness, hypocalcemia and alopecia totalis since early childhood, and were followed up for 27 years. Sequencing of the DNA extracted from the peripheral white blood cells showed a missense G to A mutation in exon number 4 (g.30994 G > A) that led to the methionine substitution for the naturally occurring valine at position 26 in the DNA binding domain (DBD) of the VDR.
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Affiliation(s)
- Ali A. Ghazi
- Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran
- Corresponding author: Ali Asghar Ghazi, MD, Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, P.O.Box: 19395-4763, 1985717413, Tehran, IR Iran. Tel: +98-2122409309, Fax: +98-2122402463, E-mail:
| | - Azita Zadeh-Vakili
- Cellular and Molecular Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran
| | - Marjan Zarif Yeganeh
- Cellular and Molecular Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran
| | - Shahram Alamdari
- Medical Research Development Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran
| | - Atieh Amouzegar
- Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran
| | - Ali Akbar Khorsandi
- Department of Orthopedics, Shafa Yahyaian Hospital, Iran University of Medical Sciences, Tehran, IR Iran
| | | | - Fereidoun Azizi
- Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran
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Futawaka K, Tagami T, Fukuda Y, Koyama R, Nushida A, Nezu S, Yamamoto H, Imamoto M, Kasahara M, Moriyama K. Transcriptional activation of the wild-type and mutant vitamin D receptors by vitamin D3 analogs. J Mol Endocrinol 2016; 57:23-32. [PMID: 27154546 DOI: 10.1530/jme-16-0048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 05/06/2016] [Indexed: 11/08/2022]
Abstract
The active form of vitamin D3 (1α,25(OH)2D3, also known as calcitriol) controls the expression of target genes via the vitamin D receptor (VDR). Vitamin D-dependent rickets type II (VDDRII) is a congenital disease caused by inactivating mutations in the VDR The condition is treated with high doses of calcitriol, but the therapeutic effects of other synthetic VD3 analogs have not yet been investigated. In the present study, we analyzed the transcriptional activity of seven different VD3 analogs with VDRs carrying ligand-binding domain mutations identified in VDDRII patients. Wild-type VDR (WT-VDR) and seven mutant VDRs were expressed in TSA201 human embryonic kidney cells, HepG2 human liver cancer cells, and MC3T3-E1 mouse calvaria cells, and their transcriptional activation with VD3 analogs were analyzed by performing transient expression assays, western blotting, and quantitative real-time PCR. The results demonstrated that falecalcitriol stimulated significantly higher transcriptional activation of the WT-VDR and some mutant VDRs than did calcitriol. Calcitriol showed almost no transcriptional activation of the VDR with the I268T mutation identified in a severe case of VDDRII, whereas falecalcitriol caused a dose-dependent increase in the activation of this mutant VDR. Our findings demonstrate that falecalcitriol has a VDR activation profile distinct from that of calcitriol and may exhibit therapeutic effects even on difficult-to-treat VDDRII cases resistant to calcitriol. It is also possible that VDDRII patients responding to high doses of calcitriol could be appropriately treated with low doses of falecalcitriol.
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Affiliation(s)
- Kumi Futawaka
- Department of Medicine and Clinical ScienceFaculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo, Japan
| | - Tetsuya Tagami
- Clinical Research Institute for Endocrine and Metabolic DiseasesNational Hospital Organization Kyoto Medical Center, Kyoto, Japan
| | - Yuki Fukuda
- Department of Medicine and Clinical ScienceFaculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo, Japan
| | - Rie Koyama
- Department of Medicine and Clinical ScienceFaculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo, Japan
| | - Ayaka Nushida
- Department of Medicine and Clinical ScienceFaculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo, Japan
| | - Shoko Nezu
- Department of Medicine and Clinical ScienceFaculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo, Japan
| | - Hironori Yamamoto
- Department of Health and NutritionFaculty of Human Life, Jin-ai University, Fukui, Japan
| | - Miyuki Imamoto
- Department of Nephrology and Blood PurificationInstitute of Biomedical Research and Innovation, Kobe Medical Frontier Center, Kobe, Japan
| | - Masato Kasahara
- Department of Nephrology and Blood PurificationInstitute of Biomedical Research and Innovation, Kobe Medical Frontier Center, Kobe, Japan
| | - Kenji Moriyama
- Department of Medicine and Clinical ScienceFaculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo, Japan Clinical Research Institute for Endocrine and Metabolic DiseasesNational Hospital Organization Kyoto Medical Center, Kyoto, Japan Department of Nephrology and Blood PurificationInstitute of Biomedical Research and Innovation, Kobe Medical Frontier Center, Kobe, Japan
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Belorusova AY, Rochel N. Structural Studies of Vitamin D Nuclear Receptor Ligand-Binding Properties. VITAMINS AND HORMONES 2015; 100:83-116. [PMID: 26827949 DOI: 10.1016/bs.vh.2015.10.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The vitamin D nuclear receptor (VDR) and its natural ligand, 1α,25-dihydroxyvitamin D3 hormone (1,25(OH)2D3, or calcitriol), classically regulate mineral homeostasis and metabolism but also much broader range of biological functions, such as cell growth, differentiation, antiproliferation, apoptosis, adaptive/innate immune responses. Being widely expressed in various tissues, VDR represents an important therapeutic target in the treatment of diverse disorders. Since ligand binding is a key step in VDR-mediated signaling, numerous 1,25(OH)2D3 analogs have been synthesized in order to selectively modulate the receptor activity. Most of the synthetic analogs have been developed by modification of a parental compound and some of them mimic 1,25(OH)2D3 scaffold without being structurally related to it. The ability of ligands that have different size and conformation to bind to VDR and to demonstrate biological effects is intriguing, and therefore, ligand-binding properties of the receptor have been extensively investigated using a variety of biochemical, biophysical, and computational methods. In this chapter, we describe different aspects of the structure-function relationship of VDR in complex with natural and synthetic ligands coming from structural analysis. With the emphasis on the binding modes of the most promising compounds, such as secosteroidal agonists and 1,25(OH)2D3 mimics, we also highlight the action of VDR antagonists and the evidence for the existence of an alternative ligand-binding site within the receptor. Additionally, we describe the crystal structures of VDR mutants associated with hereditary vitamin D-resistant rickets that display impaired ligand-binding function.
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Affiliation(s)
- Anna Y Belorusova
- Department of Integrative Structural Biology, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Institut National de Santé et de Recherche Médicale (INSERM) U964, Centre National de Recherche Scientifique (CNRS) UMR 7104, Université de Strasbourg, Illkirch, France
| | - Natacha Rochel
- Department of Integrative Structural Biology, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Institut National de Santé et de Recherche Médicale (INSERM) U964, Centre National de Recherche Scientifique (CNRS) UMR 7104, Université de Strasbourg, Illkirch, France.
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Tamura M, Isojima T, Kawashima M, Yoshida H, Yamamoto K, Kitaoka T, Namba N, Oka A, Ozono K, Tokunaga K, Kitanaka S. Detection of Hereditary 1,25-Hydroxyvitamin D-Resistant Rickets Caused by Uniparental Disomy of Chromosome 12 Using Genome-Wide Single Nucleotide Polymorphism Array. PLoS One 2015; 10:e0131157. [PMID: 26153892 PMCID: PMC4496068 DOI: 10.1371/journal.pone.0131157] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Accepted: 05/31/2015] [Indexed: 11/30/2022] Open
Abstract
Context Hereditary 1,25-dihydroxyvitamin D-resistant rickets (HVDRR) is an autosomal recessive disease caused by biallelic mutations in the vitamin D receptor (VDR) gene. No patients have been reported with uniparental disomy (UPD). Objective Using genome-wide single nucleotide polymorphism (SNP) array to confirm whether HVDRR was caused by UPD of chromosome 12. Materials and Methods A 2-year-old girl with alopecia and short stature and without any family history of consanguinity was diagnosed with HVDRR by typical laboratory data findings and clinical features of rickets. Sequence analysis of VDR was performed, and the origin of the homozygous mutation was investigated by target SNP sequencing, short tandem repeat analysis, and genome-wide SNP array. Results The patient had a homozygous p.Arg73Ter nonsense mutation. Her mother was heterozygous for the mutation, but her father was negative. We excluded gross deletion of the father’s allele or paternal discordance. Genome-wide SNP array of the family (the patient and her parents) showed complete maternal isodisomy of chromosome 12. She was successfully treated with high-dose oral calcium. Conclusions This is the first report of HVDRR caused by UPD, and the third case of complete UPD of chromosome 12, in the published literature. Genome-wide SNP array was useful for detecting isodisomy and the parental origin of the allele. Comprehensive examination of the homozygous state is essential for accurate genetic counseling of recurrence risk and appropriate monitoring for other chromosome 12 related disorders. Furthermore, oral calcium therapy was effective as an initial treatment for rickets in this instance.
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Affiliation(s)
- Mayuko Tamura
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Tsuyoshi Isojima
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Minae Kawashima
- Department of Human Genetics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hideki Yoshida
- Department of Pediatrics, North Medical Center, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Keiko Yamamoto
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Taichi Kitaoka
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Noriyuki Namba
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Akira Oka
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Keiichi Ozono
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Katsushi Tokunaga
- Department of Human Genetics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Sachiko Kitanaka
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- * E-mail:
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Damiani FM, Martin RM, Latronico AC, Ferraz-de-Souza B. Normal bone mass and normocalcemia in adulthood despite homozygous vitamin D receptor mutations. Osteoporos Int 2015; 26:1819-23. [PMID: 25708797 DOI: 10.1007/s00198-015-3076-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 02/11/2015] [Indexed: 01/05/2023]
Abstract
UNLABELLED Adding to the debate around vitamin D's effects on skeletal health, we report the long-term follow-up of two patients with severe vitamin D receptor mutations, who had normal bone mass acquisition and normalization of calcemia around puberty, suggesting that vitamin D might not be essential for skeletal health in adulthood. INTRODUCTION Vitamin D plays a pivotal role in calcium homeostasis, and the consequences of vitamin D insufficiency for skeletal health, as well as the importance of its supplementation, are a matter of great interest. Individuals bearing homozygous vitamin D receptor (VDR) defects present with severe hypocalcemic rickets in early infancy due to vitamin D resistance. METHODS Here, we report the follow-up of two patients with hereditary vitamin D-resistant rickets (HVDRR), focusing on bone mass acquisition and evolution of calcemia. RESULTS Patient 1 is a 30-year-old male bearing a homozygous p.Arg30* nonsense mutation in the VDR DNA-binding domain, who presented at 6 months. From 9 years of age, treatment requirement decreased progressively. Follow-up with DXA showed normal bone mass acquisition. In adulthood, he maintains normocalcemia without calcium supplementation and has no signs of bone fragility. Patient 2 is a 37-year-old female with milder HVDRR and alopecia due to a homozygous p.Gly319Val mutation in the VDR ligand-binding domain. Around puberty, hypercalciuria and kidney stones were detected, resulting in suspension of treatment. Follow-up with DXA revealed normal bone mass, and she maintained normocalcemia without supplementation during gestation and lactation. CONCLUSIONS The long-term follow-up of HVDRR provides insights into the role of vitamin D in human calcium homeostasis and bone health. The normalization of calcemia and normal bone mass acquisition despite a permanently dysfunctional VDR suggest that vitamin D might not be essential for skeletal health in adulthood. Extrapolation of these findings may have implications in broader clinical settings, especially considering widespread vitamin D supplementation.
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Affiliation(s)
- F M Damiani
- Division of Endocrinology and Laboratory of Medical Investigation 18 - LIM-18, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Av Dr Arnaldo, 455 sala 3324 (LIM-18), São Paulo, SP, 01246-903, Brazil
| | - R M Martin
- Division of Endocrinology and Laboratory of Medical Investigation 18 - LIM-18, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Av Dr Arnaldo, 455 sala 3324 (LIM-18), São Paulo, SP, 01246-903, Brazil
| | - A C Latronico
- Division of Endocrinology and Laboratory of Medical Investigation 18 - LIM-18, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Av Dr Arnaldo, 455 sala 3324 (LIM-18), São Paulo, SP, 01246-903, Brazil
| | - B Ferraz-de-Souza
- Division of Endocrinology and Laboratory of Medical Investigation 18 - LIM-18, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Av Dr Arnaldo, 455 sala 3324 (LIM-18), São Paulo, SP, 01246-903, Brazil.
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Papadopoulou A, Bountouvi E, Gole E, Doulgeraki A, Tournis S, Papadimitriou A, Nicolaidou P. Identification of a novel nonsense mutation in the ligand-binding domain of the vitamin d receptor gene and clinical description of two greek patients with hereditary vitamin d-resistant rickets and alopecia. Horm Res Paediatr 2015; 82:206-12. [PMID: 25060608 DOI: 10.1159/000362618] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 04/01/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS We analyzed the vitamin D receptor (VDR) gene in 2 Greek patients who exhibited the classical features of hereditary vitamin D-resistant rickets (HVDRR) type II, including severe bone deformities and alopecia. We also describe the clinical phenotypes and the response to treatment of our patients. METHODS Genomic DNA was extracted from peripheral blood samples of both patients. Coding region and flanking introns of VDR gDNA was amplified and direct sequenced. RESULTS A unique cytosine to thymine (C>T) transition was identified at nucleotide position 1066 (c.1066C>T) in the ligand-binding domain of the VDR gene of both patients, predicting the substitution of a glutamine to a terminal codon at position 356 (Gln356stop). CONCLUSIONS The novel nonsense mutation c.1066C>T (Gln356stop) is expected to result in a VDR protein 71 amino acids shorter and thus to affect the normal VDR function. In particular, the missing protein part alters the VDR heterodimerization with the retinoid X receptor which has been correlated with the presence of alopecia. Both patients were introduced to treatment with supraphysiological doses of 1α-calcidiol which improved their clinical phenotypes except for alopecia.
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Affiliation(s)
- Anna Papadopoulou
- Third Department of Pediatrics, Athens University Medical School, 'Attikon' University General Hospital, Athens, Greece
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11
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Mutations in the vitamin D receptor and hereditary vitamin D-resistant rickets. BONEKEY REPORTS 2014; 3:510. [PMID: 24818002 DOI: 10.1038/bonekey.2014.5] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 09/27/2013] [Indexed: 12/24/2022]
Abstract
Heterogeneous loss of function mutations in the vitamin D receptor (VDR) interfere with vitamin D signaling and cause hereditary vitamin D-resistant rickets (HVDRR). HVDRR is characterized by hypocalcemia, secondary hyperparathyroidism and severe early-onset rickets in infancy and is often associated with consanguinity. Affected children may also exhibit alopecia of the scalp and total body. The children usually fail to respond to treatment with calcitriol; in fact, their endogenous levels are often very elevated. Successful treatment requires reversal of hypocalcemia and secondary hyperparathyroidism and is usually accomplished by administration of high doses of calcium given either intravenously or sometimes orally to bypass the intestinal defect in VDR signaling.
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Malloy PJ, Tasic V, Taha D, Tütüncüler F, Ying GS, Yin LK, Wang J, Feldman D. Vitamin D receptor mutations in patients with hereditary 1,25-dihydroxyvitamin D-resistant rickets. Mol Genet Metab 2014; 111:33-40. [PMID: 24246681 PMCID: PMC3933290 DOI: 10.1016/j.ymgme.2013.10.014] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 10/22/2013] [Accepted: 10/23/2013] [Indexed: 02/06/2023]
Abstract
CONTEXT Hereditary vitamin D resistant rickets (HVDRR), also known as vitamin D-dependent rickets type II, is an autosomal recessive disorder characterized by the early onset of rickets with hypocalcemia, secondary hyperparathyroidism and hypophosphatemia and is caused by mutations in the vitamin D receptor (VDR) gene. The human gene encoding the VDR is located on chromosome 12 and comprises eight coding exons and seven introns. OBJECTIVES, PATIENTS, AND METHODS We analyzed the VDR gene of 5 previously unreported patients, two from Singapore and one each from Macedonia (former Yugoslav Republic), Saudi Arabia and Turkey. Each patient had clinical and radiographic features of rickets, hypocalcemia, and the 4 cases that had the measurement showed elevated serum concentrations of 1,25-dihydroxyvitamin D (1,25(OH)(2)D). Mutations were re-created in the WT VDR cDNA and examined for 1,25(OH)(2)D(3)-mediated transactivation in COS-7 monkey kidney cells. RESULTS Direct sequencing identified four novel mutations and two previously described mutations in the VDR gene. The novel mutations included a missense mutation in exon 3 causing the amino acid change C60W; a missense mutation in exon 4 causing the amino acid change D144N; a missense mutation in exon 7 causing the amino acid change N276Y; and a 2bp deletion in exon 3 5'-splice site (IVS3∆+4-5) leading to a premature stop. CONCLUSIONS These 4 unique mutations add to the previous 45 mutations identified in the VDR gene in patients with HVDRR.
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Affiliation(s)
- Peter J Malloy
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Velibor Tasic
- Department of Pediatric Nephrology, Clinic for Children's Diseases, University Children's Hospital, Medical School of Skopje, Skopje, Macedonia
| | - Doris Taha
- Department of Endocrinology, Children's Hospital of Michigan, Detroit, MI 48201, USA
| | - Filiz Tütüncüler
- Pediatric Endocrinology, Trakya University, Faculty of Medicine, Edirne, Turkey
| | - Goh Siok Ying
- Department of Pediatrics, University Children's Medical Institute, National University Hospital, Singapore
| | - Loke Kah Yin
- Department of Pediatrics, University Children's Medical Institute, National University Hospital, Singapore
| | - Jining Wang
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - David Feldman
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
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Abstract
The biochemical and genetic analysis of the VDR in patients with HVDRR has yielded important insights into the structure and function of the receptor in mediating 1,25(OH)2D3 action. Similarly, study of children affected by HVDRR continues to provide a more complete understanding of the biologic role of 1,25(OH)2D3 in vivo. A concerted investigative approach to HVDRR at the clinical, cellular, and molecular levels has proved valuable in gaining knowledge of the functions of the domains of the VDR and elucidating the detailed mechanism of action of 1,25(OH)2D3. These studies have been essential to promote the well-being of the families with HVDRR and in improving the diagnostic and clinical management of this rare genetic disease.
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Silva MRDD, Jorge AAL. Bringing endocrine basic science and physician investigators together. ARQUIVOS BRASILEIROS DE ENDOCRINOLOGIA E METABOLOGIA 2010; 54:671-672. [PMID: 21340150 DOI: 10.1590/s0004-27302010000800001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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Abstract
Two rare genetic diseases can cause rickets in children. The critical enzyme to synthesize calcitriol from 25-hydroxyvitamin D, the circulating hormone precursor, is 25-hydroxyvitamin D-1alpha-hydroxylase (1alpha-hydroxylase). When this enzyme is defective and calcitriol can no longer be synthesized, the disease 1alpha-hydroxylase deficiency develops. The disease is also known as vitamin D-dependent rickets type 1 or pseudovitamin D deficiency rickets. When the VDR is defective, the disease hereditary vitamin D-resistant rickets, also known as vitamin D-dependent rickets type 2, develops. Both diseases are rare autosomal recessive disorders characterized by hypocalcemia, secondary hyperparathyroidism, and early onset severe rickets. In this article, these 2 genetic childhood diseases, which present similarly with hypocalcemia and rickets in infancy, are discussed and compared.
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Affiliation(s)
- Peter J Malloy
- Division of Endocrinology, Gerontology and Metabolism, Stanford University School of Medicine, Stanford University, S-025 Endocrinology, Stanford, CA 94305-5103, USA.
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Kanakamani J, Tomar N, Kaushal E, Tandon N, Goswami R. Presence of a deletion mutation (c.716delA) in the ligand binding domain of the vitamin D receptor in an Indian patient with vitamin D-dependent rickets type II. Calcif Tissue Int 2010; 86:33-41. [PMID: 19921089 DOI: 10.1007/s00223-009-9310-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Accepted: 10/15/2009] [Indexed: 10/20/2022]
Abstract
Vitamin D-dependent rickets type II (VDDR-type II) is a rare disorder caused by mutations in the vitamin D receptor (VDR) gene. Here, we describe a patient with VDDR-type II with severe alopecia and rickets. She had hypocalcemia, hypophosphatemia, secondary hyperparathyroidism, and elevated serum alkaline phosphatase and 1,25-dihydroxyvitamin D(3). Sequence analysis of the lymphocyte VDR cDNA revealed deletion mutation c.716delA. Sequence analysis of her genomic DNA fragment amplified from exon 6 of the VDR gene incorporating this mutation confirmed the presence of the mutation in homozygous form. This frameshift mutation in the ligand binding domain (LBD) resulted in premature termination (p.Lys240Argfs) of the VDR protein. The mutant protein contained 246 amino acids, with 239 normal amino acids at the N terminus, followed by seven changed amino acids resulting in complete loss of its LBD. The mutant VDR protein showed evidence of 50% reduced binding with VDR response elements on electrophoretic mobility assay in comparison to the wild-type VDR protein. She was treated with high-dose calcium infusion and oral phosphate. After 18 months of treatment, she gained 6 cm of height, serum calcium and phosphorus improved, alkaline phosphatase levels decreased, and intact PTH normalized. Radiologically, there were signs of healing of rickets. Her parents and one of her siblings had the same c.716delA mutation in heterozygous form. Despite the complete absence of LBD, the rickets showed signs of healing with intravenous calcium.
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Affiliation(s)
- Jeyaraman Kanakamani
- Department of Endocrinology and Metabolism, All India Institute of Medical Sciences, New Delhi 110029, India.
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