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Bizerea-Moga TO, Chisavu F, Ilies C, Olah O, Marginean O, Gafencu M, Doros G, Stroescu R. Phenotype of Idiopathic Infantile Hypercalcemia Associated with the Heterozygous Pathogenic Variant of SLC34A1 and CYP24A1. Children (Basel) 2023; 10:1701. [PMID: 37892364 PMCID: PMC10605249 DOI: 10.3390/children10101701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 10/12/2023] [Accepted: 10/16/2023] [Indexed: 10/29/2023]
Abstract
Idiopathic infantile hypercalcemia (IIH) is a rare genetic disease, also called hypersensitivity to vitamin D3. The molecular heterogeneity allows for the differentiation between the two forms; IIH type 1 caused by CYP24A1 genetic variants and IIH type 2 associated with SLC34A1 mutations. The affected individuals express a variety of symptoms: hypercalcemia, hypercalciuria, suppressed intact parathormone levels (PTH), nephrocalcinosis, elevated levels of serum 1,25 (OH)2-vitamin D3 or inappropriately normal levels, and kidney phosphate wasting. The present paper describes three cases of IIH with heterozygous mutations in SLC34A1 and CYP24A1 genes, respectively. The genetic diagnosis is of paramount importance for proper treatment and the prediction of long-term outcomes.
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Affiliation(s)
- Teofana Otilia Bizerea-Moga
- Department XI of Pediatrics—1st Pediatric Discipline, Center for Research on Growth and Developmental Disorders in Children, ‘Victor Babeș’ University of Medicine and Pharmacy Timișoara, Eftimie Murgu Sq. No. 2, 300041 Timișoara, Romania; (T.O.B.-M.); (O.M.); (R.S.)
- 1st Pediatric Clinic, ‘Louis Țurcanu’ Children’s Clinical and Emergency Hospital, Iosif Nemoianu 2, 300011 Timișoara, Romania; (C.I.); (O.O.)
| | - Flavia Chisavu
- 4th Pediatric Clinic, ‘Louis Țurcanu’ Children’s Clinical sand Emergency Hospital, Iosif Nemoianu 2, 300011 Timișoara, Romania; (M.G.); (G.D.)
- Centre for Molecular Research in Nephrology and Vascular Disease, Faculty of Medicine ‘Victor Babes’, 300041 Timișoara, Romania
| | - Cristina Ilies
- 1st Pediatric Clinic, ‘Louis Țurcanu’ Children’s Clinical and Emergency Hospital, Iosif Nemoianu 2, 300011 Timișoara, Romania; (C.I.); (O.O.)
- Department III of Functional Sciences—Pathophysiology Discipline, ‘Victor Babeș’ University of Medicine and Pharmacy Timișoara, Eftimie Murgu Sq. No. 2, 300041 Timișoara, Romania
| | - Orsolya Olah
- 1st Pediatric Clinic, ‘Louis Țurcanu’ Children’s Clinical and Emergency Hospital, Iosif Nemoianu 2, 300011 Timișoara, Romania; (C.I.); (O.O.)
- Department VIII of Neuroscience—Psychology Discipline, ‘Victor Babeș’ University of Medicine and Pharmacy Timișoara, Eftimie Murgu Sq. No. 2, 300041 Timișoara, Romania
| | - Otilia Marginean
- Department XI of Pediatrics—1st Pediatric Discipline, Center for Research on Growth and Developmental Disorders in Children, ‘Victor Babeș’ University of Medicine and Pharmacy Timișoara, Eftimie Murgu Sq. No. 2, 300041 Timișoara, Romania; (T.O.B.-M.); (O.M.); (R.S.)
- 1st Pediatric Clinic, ‘Louis Țurcanu’ Children’s Clinical and Emergency Hospital, Iosif Nemoianu 2, 300011 Timișoara, Romania; (C.I.); (O.O.)
| | - Mihai Gafencu
- 4th Pediatric Clinic, ‘Louis Țurcanu’ Children’s Clinical sand Emergency Hospital, Iosif Nemoianu 2, 300011 Timișoara, Romania; (M.G.); (G.D.)
- Department XI of Pediatrics—3rd Pediatric Discipline, ‘Victor Babeș’ University of Medicine and Pharmacy Timișoara, Eftimie Murgu Sq. No. 2, 300041 Timișoara, Romania
| | - Gabriela Doros
- 4th Pediatric Clinic, ‘Louis Țurcanu’ Children’s Clinical sand Emergency Hospital, Iosif Nemoianu 2, 300011 Timișoara, Romania; (M.G.); (G.D.)
- Department XI of Pediatrics—3rd Pediatric Discipline, ‘Victor Babeș’ University of Medicine and Pharmacy Timișoara, Eftimie Murgu Sq. No. 2, 300041 Timișoara, Romania
| | - Ramona Stroescu
- Department XI of Pediatrics—1st Pediatric Discipline, Center for Research on Growth and Developmental Disorders in Children, ‘Victor Babeș’ University of Medicine and Pharmacy Timișoara, Eftimie Murgu Sq. No. 2, 300041 Timișoara, Romania; (T.O.B.-M.); (O.M.); (R.S.)
- 4th Pediatric Clinic, ‘Louis Țurcanu’ Children’s Clinical sand Emergency Hospital, Iosif Nemoianu 2, 300011 Timișoara, Romania; (M.G.); (G.D.)
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St-Arnaud R, Arabian A, Kavame D, Kaufmann M, Jones G. Vitamin D and Diseases of Mineral Homeostasis: A Cyp24a1 R396W Humanized Preclinical Model of Infantile Hypercalcemia Type 1. Nutrients 2022; 14:nu14153221. [PMID: 35956396 PMCID: PMC9370611 DOI: 10.3390/nu14153221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 08/03/2022] [Accepted: 08/04/2022] [Indexed: 11/17/2022] Open
Abstract
Infantile hypercalcemia type 1 (HCINF1), previously known as idiopathic infantile hypercalcemia, is caused by mutations in the 25-hydroxyvitamin D 24-hydroxylase gene, CYP24A1. The R396W loss-of-function mutation in CYP24A1 is the second most frequent mutated allele observed in affected HCINF1 patients. We have introduced the site-specific R396W mutation within the murine Cyp24a1 gene in knock-in mice to generate a humanized model of HCINF1. On the C57Bl6 inbred background, homozygous mutant mice exhibited high perinatal lethality with 17% survival past weaning. This was corrected by crossbreeding to the CD1 outbred background. Mutant animals had hypercalcemia in the first week of life, developed nephrolithiasis, and had a very high 25(OH)D3 to 24,25(OH)2D3 ratio which is a diagnostic hallmark of the HCINF1 condition. Expression of the mutant Cyp24a1 allele was highly elevated while Cyp27b1 expression was abrogated. Impaired bone fracture healing was detected in CD1-R396w/w mutant animals. The augmented lethality of the C57Bl6-R396W strain suggests an influence of distinct genetic backgrounds. Our data point to the utility of unique knock-in mice to probe the physiological ramifications of CYP24A1 variants in isolation from other biological and environmental factors.
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Affiliation(s)
- René St-Arnaud
- Research Centre, Shriners Hospital for Children-Canada, Montreal, QC H4A 0A9, Canada
- Department of Human Genetics, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H3A 0C7, Canada
- Department of Surgery, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H3G 1A4, Canada
- Department of Medicine, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H3A 1A1, Canada
- Correspondence: ; Tel.: +1-514-282-7155; Fax: +1-514-842-5581
| | - Alice Arabian
- Research Centre, Shriners Hospital for Children-Canada, Montreal, QC H4A 0A9, Canada
| | - Dila Kavame
- Research Centre, Shriners Hospital for Children-Canada, Montreal, QC H4A 0A9, Canada
- Department of Human Genetics, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H3A 0C7, Canada
| | - Martin Kaufmann
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, ON K7L 3N6, Canada
- Department of Surgery, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - Glenville Jones
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, ON K7L 3N6, Canada
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Pilz S, Theiler-Schwetz V, Pludowski P, Zelzer S, Meinitzer A, Karras SN, Misiorowski W, Zittermann A, März W, Trummer C. Hypercalcemia in Pregnancy Due to CYP24A1 Mutations: Case Report and Review of the Literature. Nutrients 2022; 14:2518. [PMID: 35745247 DOI: 10.3390/nu14122518] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 06/12/2022] [Accepted: 06/14/2022] [Indexed: 02/06/2023] Open
Abstract
Pathogenic mutations of CYP24A1 lead to an impaired catabolism of vitamin D metabolites and should be considered in the differential diagnosis of hypercalcemia with low parathyroid hormone concentrations. Diagnosis is based on a reduced 24,25-dihydroxyvitamin D to 25-hydroxyvitamin D ratio and confirmed by genetic analyses. Pregnancy is associated with an upregulation of the active vitamin D hormone calcitriol and may thus particularly trigger hypercalcemia in affected patients. We present a case report and a narrative review of pregnant women with CYP24A1 mutations (13 women with 29 pregnancies) outlining the laboratory and clinical characteristics during pregnancy and postpartum and the applied treatment approaches. In general, pregnancy triggered hypercalcemia in the affected women and obstetric complications were frequently reported. Conclusions on drugs to treat hypercalcemia during pregnancy are extremely limited and do not show clear evidence of efficacy. Strictly avoiding vitamin D supplementation seems to be effective in preventing or reducing the degree of hypercalcemia. Our case of a 24-year-old woman who presented with hypercalcemia in the 24th gestational week delivered a healthy baby and hypercalcemia resolved while breastfeeding. Pathogenic mutations of CYP24A1 mutations are rare but should be considered in the context of vitamin D supplementation during pregnancy.
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Brancatella A, Cappellani D, Kaufmann M, Borsari S, Piaggi P, Baldinotti F, Caligo MA, Jones G, Marcocci C, Cetani F. Do the Heterozygous Carriers of a CYP24A1 Mutation Display a Different Biochemical Phenotype Than Wild Types? J Clin Endocrinol Metab 2021; 106:708-717. [PMID: 33249478 DOI: 10.1210/clinem/dgaa876] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Indexed: 01/07/2023]
Abstract
CONTEXT Human cytochrome P450 24 subfamily A member 1 (CYP24A1) loss-of-function mutations result in impaired activity of the 24-hydroxylase involved in vitamin D catabolism, thus inducing a vitamin D-dependent hypercalcemia. Homozygotes often present an overt clinical phenotype named idiopathic infantile hypercalcemia (IIH), whereas it is debated whether heterozygotes display an abnormal phenotype. OBJECTIVE To compare the clinical and biochemical features of heterozygous carriers of CYP24A1 variant and healthy wild-type controls sharing the same genetic and environmental exposure. METHODS A large family harboring the nonsense c.667A>T, p.Arg223* pathogenic variant in the CYP24A1 gene was evaluated. All subjects underwent clinical and biochemical evaluation and complete analysis of vitamin D metabolites using mass spectroscopy including 1,24,25(OH)3D3. Subjects were divided into 2 groups according to their genotype: heterozygotes and wild-type for the CYP24A1 variant. RESULTS The proband, a 40-year-old man, homozygous for p.Arg223* pathogenic variant, had a history of mild hypercalcemia with a seasonal trend, recurrent nephrolithiasis, and no episodes of acute hypercalcemia. He showed the highest serum levels of fibroblast growth factor 23, the highest 25(OH)D3/24,25(OH)2D3 ratio and undetectable levels of 1,24,25(OH)3D3, which represent indicators of a loss-of-function CYP24A1. Compared with the wild-types, heterozygotes had higher serum calcium and 25(OH)D3 concentrations (P = .017 and P = .025, respectively), without any difference in the other biochemical parameters and in the rate of nephrolithiasis. CONCLUSION Heterozygotes exhibit a biochemical phenotype different from that of wild-type subjects. In clinical practice, these individuals might require surveillance because of the potential risk of developing hypercalcemia and related clinical manifestations if exposed to triggering factors.
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Affiliation(s)
- Alessandro Brancatella
- Department of Clinical and Experimental Medicine, Unit of Endocrinology, University of Pisa, Pisa, Italy
| | - Daniele Cappellani
- Department of Clinical and Experimental Medicine, Unit of Endocrinology, University of Pisa, Pisa, Italy
| | - Martin Kaufmann
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
| | - Simona Borsari
- Department of Clinical and Experimental Medicine, Unit of Endocrinology, University of Pisa, Pisa, Italy
| | - Paolo Piaggi
- Department of Information Engineering, University of Pisa, Pisa, Italy
| | | | | | - Glenville Jones
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
| | - Claudio Marcocci
- Department of Clinical and Experimental Medicine, Unit of Endocrinology, University of Pisa, Pisa, Italy
| | - Filomena Cetani
- Department of Clinical and Experimental Medicine, Unit of Endocrinology, University of Pisa, Pisa, Italy
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De Paolis E, Scaglione GL, De Bonis M, Minucci A, Capoluongo E. CYP24A1 and SLC34A1 genetic defects associated with idiopathic infantile hypercalcemia: from genotype to phenotype. Clin Chem Lab Med 2020; 57:1650-1667. [PMID: 31188746 DOI: 10.1515/cclm-2018-1208] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 02/22/2019] [Indexed: 02/07/2023]
Abstract
Loss of function mutations in the CYP24A1 gene, involved in vitamin D catabolism and in calcium homeostasis, are known to be the genetic drivers of both idiopathic infantile hypercalcemia (IIH) and adult renal stone disease. Recently, also defects in the SLC34A1 gene, encoding for the renal sodium-phosphate transporter NaPi-IIa, were associated with the disease. IIH typically affects infants and pediatric patients with a syndrome characterized by severe hypercalcemia, hypercalciuria, suppressed parathyroid hormone level and nephrolithiasis. In SLC34A1 mutated carriers, hypophosphatemia is also a typical biochemical tract. IIH may also persist undiagnosed into adulthood, causing an increased risk of nephrocalcinosis and renal complication. To note, a clinical heterogeneity characterizes IIH manifestation, principally due to the controversial gene-dose effect and, to the strong influence of environmental factors. The present review is aimed to provide an overview of the current molecular findings on the IIH disorder, giving a comprehensive description of the association between genotype and biochemical and clinical phenotype of the affected patients. We also underline that patients may benefit from genetic testing into a targeted diagnostic and therapeutic workflow.
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Affiliation(s)
- Elisa De Paolis
- Laboratory of Molecular Diagnostics and Genomics, Teaching and Research Hospital "Fondazione Policlinico Agostino Gemelli" - IRCCS, Catholic University of the Sacred Heart, Rome, Italy
| | - Giovanni Luca Scaglione
- Laboratory of Molecular Oncology, "Fondazione Giovanni Paolo II", Catholic University of Sacred Heart, Campobasso, Italy
| | - Maria De Bonis
- Laboratory of Molecular Diagnostics and Genomics, Teaching and Research Hospital "Fondazione Policlinico Agostino Gemelli" - IRCCS, Catholic University of the Sacred Heart, Rome, Italy
| | - Angelo Minucci
- Laboratory of Molecular Diagnostics and Genomics, Teaching and Research Hospital "Fondazione Policlinico Agostino Gemelli" - IRCCS, Catholic University of the Sacred Heart, Rome, Italy
| | - Ettore Capoluongo
- Laboratory of Molecular Diagnostics and Genomics, Teaching and Research Hospital "Fondazione Policlinico Agostino Gemelli" - IRCCS, Catholic University of the Sacred Heart, Rome, Italy
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Güven A, Konrad M, Schlingmann KP. Idiopathic infantile hypercalcemia: mutations in SLC34A1 and CYP24A1 in two siblings and fathers. J Pediatr Endocrinol Metab 2020; 33:1353-1358. [PMID: 32866123 DOI: 10.1515/jpem-2020-0169] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 06/15/2020] [Indexed: 11/15/2022]
Abstract
Objectives Both CYP24A1 and SLC34A1 gene mutations are responsible for idiopathic infantile hypercalcemia, whereas loss-of-function mutations in CYP24A1 (25-OH-vitamin D-24-hydroxylase) lead to a defect in the inactivation of active 1.25(OH)2D; mutations in SLC34A1 encoding renal sodium phosphate cotransporter NaPi-IIa lead to primary renal phosphate wasting combined with an inappropriate activation of vitamin D. The presence of mutations in both genes has not been reported in the same patient until today. Case presentation Hypercalcemia was incidentally detected when a 13-month-old boy was being examined for urinary tract infection. After 21 months, hypercalcemia was detected in his six-month-old sister. High dose of vitamin D was not given to both siblings. Both of them also had hypophosphatemia and decreased tubular phosphate reabsorption. Intensive hydration, furosemide and oral phosphorus treatment were given. Bilateral medullary nephrocalcinosis was detected in both siblings and their father. Serum Ca and P levels were within normal limits at follow-up in both siblings. Siblings and their parents all carry a homozygous stop codon mutation (p.R466*) in CYP24A1. Interestingly, both siblings and the father also have a heterozygous splice-site mutation (IVS6(+1)G>A) in SLC34A1. The father has nephrocalcinosis. Conclusions A biallelic loss-of-function mutation in the CYP24A1 gene was identified as responsible for hypercalcemia, hypercalciuria and nephrocalcinosis. In addition, a heterozygous mutation in the SLC34A1 gene, although not being the main pathogenic factor, might contribute to the severe phenotype of both patients.
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Affiliation(s)
- Ayla Güven
- University of Health Science, Zeynep Kamil Women and Children Hospital, Pediatric Endocrinology Clinic, Istanbul, Turkey
| | - Martin Konrad
- Department of General Pediatrics, University Children's Hospital Münster, Münster, Germany
| | - Karl P Schlingmann
- Department of General Pediatrics, University Children's Hospital Münster, Münster, Germany
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Abstract
BACKGROUND Biallelic pathogenic variants in CYP24A1 can cause idiopathic infantile hypercalcemia (HCINF). METHODS We report 2 additional molecular abnormalities in 2 Chinese children with CHINF1. RESULTS Biallelic variants in CYP24A1 were found in two patients. Patient One was compound heterozygous for c.449 + 1G > T and c.1426_1427delCT. Patient Two was compound heterozygous for c.1310C > A and c.1426_1427delCT. The c.1310C > A and c.449 + 1G > T were two different novel CYP24A1 variants. Multiple computational tools predicted that both impact protein function. A total of 36 variants have been previously reported in patients with HCINF1, of which 27 were classified as pathogenic or likely pathogenic and nine as uncertain clinical significance. CONCLUSION Genetic tests are helpful in order to counsel the susceptible individuals to avoid vitamin D and take preventive measures in order to avoid complications.
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Affiliation(s)
- Yan Sun
- a Shandong Provincial Hospital Affiliated to Shandong University , Jinan , China
| | - Jun Shen
- b Department of Pathology, Brigham and Women's Hospital , Harvard Medical School , Boston , MA , USA
| | - Xuyun Hu
- c Shanghai Children's Medical Center , Shanghai Jiao Tong University School of Medicine , Shanghai , China.,d Beijing Key Laboratory for Genetics of Birth Defects, Beijing Pediatric Research Institute; Genetics and Birth Defects Control Center, National Center for Children's Health; MOE Key Laboratory of Major Diseases in Children; Beijing Children's Hospital , Capital Medical University, Beijing , China
| | - Yu Qiao
- a Shandong Provincial Hospital Affiliated to Shandong University , Jinan , China
| | - Jianmei Yang
- a Shandong Provincial Hospital Affiliated to Shandong University , Jinan , China
| | - Yiping Shen
- c Shanghai Children's Medical Center , Shanghai Jiao Tong University School of Medicine , Shanghai , China.,e Division of Genetics and Genomics , Boston Children's Hospital, Harvard Medical School , Boston , MA , USA.,f The Maternity and Child Health Hospital of Guangxi , Nanning , China
| | - Guimei Li
- a Shandong Provincial Hospital Affiliated to Shandong University , Jinan , China
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Abstract
OBJECTIVE This study aimed to call attention to hypercalcemia, a rare finding in children which carries the potential of leading to serious complications without proper intervention. METHODS Diagnosis, treatment, and clinical course of children with sustained hypercalcemia admitted between the years 2006-2016 were reviewed. Group 1 [parathyroid hormone (PTH)-dependent] consisted of patients with high/unsuppressed PTH levels and group 2 (PTH-independent) included cases with normal/suppressed PTH levels. RESULTS Twenty patients (11 male, 9 female) with a median age of 6.25 (0.03-17.88) years were evaluated. Symptoms were mostly related with the gastrointestinal system, while six patients (30%) were asymptomatic. Physical examination findings were diverse, non-specific, and normal in four patients (20%). Median time of diagnosis was 45 (2-720) days. Patients were divided into group 1 (n=7) and group 2 (n=13). Most frequent etiologies were primary hyperparathyroidism (n=5), idiopathic infantile hypercalcemia (IIH) (n=5), and malignancy (n=4). A moderate positive correlation was noted between serum calcium and creatinine levels (r=0.53, p=0.02). Nephrocalcinosis was the most common complication (n=9) (45%). Treatment was not implemented in 2 patients with mild hypercalcemia, while other patients received medical treatment ± surgery. Treatment-resistant patients were cases of malignancies and neonatal severe hyperparathyroidism. Long-term follow-up displayed resistant hypercalciuria in three infants diagnosed as IIH. CONCLUSION Many patients with childhood hypercalcemia are asymptomatic or exhibit a non-specific and heterogeneous clinical presentation, resulting in delayed diagnosis. Mild cases may not be recognized, while symptoms may be missed in the presence of accompanying illnesses. Nevertheless, serious complications may only be avoided with prompt diagnosis and intervention.
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Affiliation(s)
- Nisa Eda Çullas İlarslan
- Ankara University Faculty of Medicine, Department of Pediatrics, Ankara, Turkey
,* Address for Correspondence: Ankara University Faculty of Medicine, Department of Pediatrics, Ankara, Turkey Phone: +90 312 595 57 63 E-mail:
| | - Zeynep Şıklar
- Ankara University Faculty of Medicine, Department of Pediatric Endocrinology, Ankara, Turkey
| | - Merih Berberoğlu
- Ankara University Faculty of Medicine, Department of Pediatric Endocrinology, Ankara, Turkey
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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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