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Disorders of the Calcium Sensing Signaling Pathway: From Familial Hypocalciuric Hypercalcemia (FHH) to Life Threatening Conditions in Infancy. J Clin Med 2022; 11:jcm11092595. [PMID: 35566721 PMCID: PMC9100033 DOI: 10.3390/jcm11092595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/29/2022] [Accepted: 05/01/2022] [Indexed: 11/23/2022] Open
Abstract
Familial hypocalciuric hypercalcemia (FHH) is a mostly benign condition of elevated calcium and PTH levels based on a hyposensitive calcium sensing receptor (CaSR) in FHH 1 or its downstream regulatory pathway in FHH2 and FHH3. In children, adolescents and young adults with FHH the main challenge is to distinguish the condition from primary hyperparathyroidism and thereby to avoid unnecessary treatments including parathyroidectomy. However, inheritance of FHH may result in neonatal hyperparathyroidism (NHPT) or neonatal severe hyperparathyroidism (NSHPT), conditions with high morbidity, and in the latter even high mortality. This review focuses on the genetic and pathophysiological framework that leads to the severe neonatal form, gives recommendations for counselling and summarizes treatment options.
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Hassan SS, Kempers M, Lugtenberg D, Abdallah AT, Musa SA, Ibrahim AA, Abdullah MA. Challenges in diagnosis and management of neonatal hyperparathyroidism in a resource-limited country: a case series from a Sudanese family. Pan Afr Med J 2021; 40:105. [PMID: 34887979 PMCID: PMC8627147 DOI: 10.11604/pamj.2021.40.105.29527] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 08/14/2021] [Indexed: 12/18/2022] Open
Abstract
Neonatal hyperparathyroidism is a rare disease caused by a homozygous inactivating mutation in the calcium sensing receptor gene. It presents early in life with life threatening manifestations of hypercalcemia, if left untreated the condition may be lethal. This is the first case series reported from Sudan. Three Sudanese siblings presented with severe symptoms of hypercalcemia in the form of polyuria, failure to thrive and multiple bone fractures. Serum calcium and parathyroid hormone levels were very high with low phosphate and normal alkaline phosphatase levels. Ultrasonography and sestamibi scan were normal and did not assist in diagnosing their condition. Medical management was a great challenge due to unavailability of medications such as parentral bisphosphonates and calcimimetics. Parathyroidectomy was inevitable. Tissue biopsies revealed parathyroid hyperplasia and no adenoma. Gene sequencing revealed a homozygous missense mutation: c 2038 C T p (Arg680Cys) in two siblings, both parents were heterozygous for the same missense mutation. Our report reflects the challenges in diagnosis and management of neonatal hyperparathyroidism in resource limited countries. We also highlight the importance of genetic testing in the diagnosis and management of such cases in countries with high rates of consanguineous marriage.
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Affiliation(s)
- Samar Sabir Hassan
- Department of Pediatric Endocrinology, Gaafar Ibn Auf Pediatric Tertiary Hospital, Khartoum, Sudan
| | | | | | | | - Salwa Abdelbagi Musa
- Department of Pediatric Endocrinology, Gaafar Ibn Auf Pediatric Tertiary Hospital, Khartoum, Sudan
| | - Areej Ahmed Ibrahim
- Department of Pediatric Endocrinology, Gaafar Ibn Auf Pediatric Tertiary Hospital, Khartoum, Sudan
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3
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Abstract
Extracellular calcium is normally tightly regulated by parathyroid hormone (PTH), 1,25-dihydroxyvitamin D, as well as by calcium ion (Ca++) itself. Dysregulated PTH production leading to hypercalcemia occurs most commonly in sporadic primary hyperparathryoidism (PHPT) but may also result from select genetic mutations in familial disorders. Parathyroid hormone-related protein shares molecular mechanisms of action with PTH and is the most common cause of hypercalcemia of malignancy. Other cytokines and mediators may also cause resorptive hypercalcemia once bone metastases have occurred. Less commonly, extrarenal production of calcitriol can occur in malignancies and in infectious and noninfectious inflammatory conditions and can cause hypercalcemia.
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Affiliation(s)
- David Goltzman
- Calcium Research Laboratory, Department of Medicine and Physiology, McGill University, Research Institute of the McGill University Health Centre, Glen Site, 1001 Decarie Boulevard, Room EM1.3220, Montreal, Quebec H4A 3J1, Canada.
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4
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Prenatal features and neonatal management of severe hyperparathyroidism caused by the heterozygous inactivating calcium-sensing receptor variant, Arg185Gln: A case report and review of the literature. Bone Rep 2021; 15:101097. [PMID: 34169121 PMCID: PMC8209172 DOI: 10.1016/j.bonr.2021.101097] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Revised: 05/25/2021] [Accepted: 06/01/2021] [Indexed: 12/27/2022] Open
Abstract
Background Loss-of-function variants in the calcium-sensing receptor (CASR) gene are known to be involved in a clinical spectrum ranging from asymptomatic familial hypocalciuric hypercalcemia (FHH) to neonatal severe hyperparathyroidism (NSHPT). Homozygous or compound heterozygous variants are usually responsible for severe neonatal forms, whereas heterozygous variants cause benign forms. One recurrent pathogenic variant, p.Arg185Gln, has been reported in both forms, in a heterozygous state. This variant can be a de novo occurrence or can be inherited from a father with FHH. NSHPT leads to global hypotonia, failure to thrive, typical X-ray anomalies (diffuse demineralization, fractures, metaphyseal irregularities), and acute respiratory distress which can be fatal. Phosphocalcic markers show severe hypercalcemia, abnormal urinary calcium resorption, and hyperparathyroidism as major signs. Classical treatment involves calcium restriction, hyperhydration, and bisphosphonates. Unfortunately, the disease often leads to parathyroidectomy. Recently, calcimimetics have been used with variable efficacy. Efficacy in NSHPT seems to be particularly dependent on CASR genotype. Case presentation We describe the antenatal presentation of a male with short ribs, initially suspected having skeletal ciliopathy. At birth, he presented with NSHPT linked to the pathogenic heterozygous CASR variant, Arg185Gln, inherited from his father who had FHH. Postnatal therapy with cinacalcet was successful. Discussion An exhaustive literature review permits a comparison with all reported cases of Arg185Gln and to hypothesize that cinacalcet efficacy depends on CASR genotype. This confirms the importance of pedigree and parental history in antenatal short rib presentation and questions the feasibility of phosphocalcic exploration during pregnancy or prenatal CASR gene sequencing in the presence of specific clinical signs. It could in fact enable early calcimimetic treatment which might be effective in the CASR variant Arg185Gln.
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Höppner J, Lais S, Roll C, Wegener-Panzer A, Wieczorek D, Högler W, Grasemann C. Case Report: Severe Neonatal Course in Paternally Derived Familial Hypocalciuric Hypercalcemia. Front Endocrinol (Lausanne) 2021; 12:700612. [PMID: 34659108 PMCID: PMC8518617 DOI: 10.3389/fendo.2021.700612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 09/06/2021] [Indexed: 12/23/2022] Open
Abstract
Familial hypocalciuric hypercalcemia (FHH, [OMIM #145980]) is recognized as a benign endocrine condition affecting PTH and calcium levels due to heterozygous inactivating mutations in the calcium sensing receptor (CaSR). The condition is often un- or misdiagnosed but may have a prevalence as high as 74 in 100.000. Here, the neonatal courses of two brothers with paternally inherited FHH (CaSR c.554G>A; p.(Arg185Gln)) are described. The older brother was born preterm at 25 weeks gestation with hypercalcemia and hyperparathyroidism. The younger brother, born full-term, had severe hyperparathyroidism, muscular hypotonia, thrombocytopenia, failure to thrive and multiple metaphyseal fractures. Treatment with cinacalcet was initiated, which resulted in subsequent reduction of PTH levels and prompt clinical improvement. While it is known that homozygous mutations in CaSR may lead to life-threatening forms of neonatal severe hyperparathyroidism (NSHPT), few reports have described a severe clinical course in neonates with FHH due to heterozygous mutations. However, based on the pathophysiological framework, in de novo or paternally transmitted FHH the differing calcium needs of mother and fetus can be expected to induce fetal hyperparathyroidism and may result in severe perinatal complications as described in this report. In summary, FHH is a mostly benign condition, but transient neonatal hyperparathyroidism may occur in affected neonates if the mutation is paternally inherited. If severe, the condition can be treated successfully with cinacalcet. Patients with FHH should be informed about the risk of neonatal disease manifestation in order to monitor pregnancies and neonates.
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MESH Headings
- Calcium/metabolism
- Heat-Shock Proteins/genetics
- Humans
- Hypercalcemia/complications
- Hypercalcemia/congenital
- Hyperparathyroidism, Primary/etiology
- Hyperparathyroidism, Primary/metabolism
- Hyperparathyroidism, Primary/pathology
- Infant, Newborn
- Infant, Newborn, Diseases/etiology
- Infant, Newborn, Diseases/metabolism
- Infant, Newborn, Diseases/pathology
- Male
- Mutation
- Paternal Inheritance
- Prognosis
- Scavenger Receptors, Class A/genetics
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Affiliation(s)
- Jakob Höppner
- Department of Pediatrics, St Josef-Hospital Bochum, Ruhr-University Bochum, Bochum, Germany
| | - Sabrina Lais
- Department of Neonatology, Pediatric Intensive Care and Sleep Medicine, Vestische Kinder- und Jugendklinik Datteln, University Witten/Herdecke, Datteln, Germany
| | - Claudia Roll
- Department of Neonatology, Pediatric Intensive Care and Sleep Medicine, Vestische Kinder- und Jugendklinik Datteln, University Witten/Herdecke, Datteln, Germany
| | - Andreas Wegener-Panzer
- Department of Radiology, Vestische Kinder- und Jugendklinik Datteln, University Witten/Herdecke, Datteln, Germany
| | - Dagmar Wieczorek
- Institute of Human Genetics, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Wolfgang Högler
- Department of Paediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria
| | - Corinna Grasemann
- Department of Pediatrics, St Josef-Hospital Bochum, Ruhr-University Bochum, Bochum, Germany
- *Correspondence: Corinna Grasemann,
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6
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Marx SJ, Sinaii N. Neonatal Severe Hyperparathyroidism: Novel Insights From Calcium, PTH, and the CASR Gene. J Clin Endocrinol Metab 2020; 105:5645387. [PMID: 31778168 PMCID: PMC7111126 DOI: 10.1210/clinem/dgz233] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 11/26/2019] [Indexed: 12/24/2022]
Abstract
CONTEXT Neonatal severe hyperparathyroidism (NSHPT) is rare and potentially lethal. It is usually from homozygous or heterozygous germline-inactivating CASR variant(s). NSHPT shows a puzzling range of serum calcium and parathyroid hormone (PTH) levels. Optimal therapy is unclear. EVIDENCE ACQUISITION We categorized genotype/phenotype pairings related to CASRs. For the 2 pairings in NSHPT, each of 57 cases of neonatal severe hyperparathyroidism required calcium, PTH, upper normal PTH, and dosage of a germline pathogenic CASR variant. EVIDENCE SYNTHESIS Homozygous and heterozygous NSHPT are 2 among a spectrum of 9 genotype/phenotype pairings relating to CASRs and NSHPT. For the 2 NSHPT pairings, expressions differ in CASR allelic dosage, CASR variant severity, and sufficiency of maternofetal calcium fluxes. Homozygous dosage of CASR variants was generally more aggressive than heterozygous. Among heterozygotes, high-grade CASR variants in vitro were more pathogenic in vivo than low-grade variants. Fetal calcium insufficiency as from maternal hypoparathyroidism caused fetal secondary hyperparathyroidism, which persisted and was reversible in neonates. Among NSHPT pairings, calcium and PTH were higher in CASR homozygotes than in heterozygotes. Extreme hypercalcemia (above 4.5 mM; normal 2.2-2.6 mM) is a robust biomarker, occurring only in homozygotes (83% of that pairing). It could occur during the first week. CONCLUSIONS In NSHPT pairings, the homozygotes for pathogenic CASR variants show higher calcium and PTH levels than heterozygotes. Calcium levels above 4.5 mM among NSHPT are frequent and unique only to most homozygotes. This cutoff supports early and robust diagnosis of CASR dosage. Thereby, it promotes definitive total parathyroidectomy in most homozygotes.
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MESH Headings
- Biomarkers/analysis
- Calcium/blood
- Female
- Genotype
- Heterozygote
- Homozygote
- Humans
- Hyperparathyroidism, Primary/blood
- Hyperparathyroidism, Primary/diagnosis
- Hyperparathyroidism, Primary/genetics
- Infant, Newborn
- Infant, Newborn, Diseases/blood
- Infant, Newborn, Diseases/diagnosis
- Infant, Newborn, Diseases/genetics
- Male
- Mutation
- Parathyroid Hormone/blood
- Prognosis
- Receptors, Calcium-Sensing/genetics
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Affiliation(s)
- Stephen J Marx
- Office of the Scientific Director, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), Bethesda, MD
- Correspondence: Stephen Marx MD, N.I.H., Bld 6A, Room 2A-04A, MSC 0614, 6 Center Drive, Bethesda, MD 20892, USA. E-mail:
| | - Ninet Sinaii
- Biostatistics and Clinical Epidemiology Service, National Institutes of Health Clinical Center, Bethesda, MD
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7
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Atypical skeletal manifestations of rickets in a familial hypocalciuric hypercalcemia patient. Bone Res 2017; 5:17001. [PMID: 28690912 PMCID: PMC5486235 DOI: 10.1038/boneres.2017.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 10/03/2016] [Accepted: 11/15/2016] [Indexed: 11/19/2022] Open
Abstract
Familial hypocalciuric hypercalcemia (FHH) is caused by inactivating mutations in the calcium-sensing receptor (CaSR) gene. The loss of function of CaSR presents with rickets as the predominant skeletal abnormality in mice, but is rarely reported in humans. Here we report a case of a 16-year-old boy with FHH who presented with skeletal manifestations of rickets. To identify the possible pathogenic mutation, the patient was evaluated clinically, biochemically, and radiographically. The patient and his family members were screened for genetic mutations. Physical examination revealed a pigeon breast deformity and X-ray examinations showed epiphyseal broadening, both of which indicate rickets. Biochemical tests also showed increased parathyroid hormone (PTH), 1,25-dihydroxyvitamin D, and elevated ionized calcium. Based on these results, a diagnosis of FHH was suspected. Sequence analysis of the patient’s CaSR gene revealed a new missense mutation (c.2279T>A) in exon 7, leading to the damaging amino change (p.I760N) in the mature CaSR protein, confirming the diagnosis of FHH. Moreover, the skeletal abnormities may be related to but not limited to vitamin D abnormity. Elevated PTH levels and a rapid skeletal growth period in adolescence may have also contributed. Our study revealed that rickets-like features have a tendency to present atypically in FHH patients who have a mild vitamin D deficiency, and that CaSR mutations may have a partial role in the pathogenesis of skeletal deformities.
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8
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Robinson-Cohen C, Lutsey PL, Kleber ME, Nielson CM, Mitchell BD, Bis JC, Eny KM, Portas L, Eriksson J, Lorentzon M, Koller DL, Milaneschi Y, Teumer A, Pilz S, Nethander M, Selvin E, Tang W, Weng LC, Wong HS, Lai D, Peacock M, Hannemann A, Völker U, Homuth G, Nauk M, Murgia F, Pattee JW, Orwoll E, Zmuda JM, Riancho JA, Wolf M, Williams F, Penninx B, Econs MJ, Ryan KA, Ohlsson C, Paterson AD, Psaty BM, Siscovick DS, Rotter JI, Pirastu M, Streeten E, März W, Fox C, Coresh J, Wallaschofski H, Pankow JS, de Boer IH, Kestenbaum B. Genetic Variants Associated with Circulating Parathyroid Hormone. J Am Soc Nephrol 2017; 28:1553-1565. [PMID: 27927781 PMCID: PMC5407713 DOI: 10.1681/asn.2016010069] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 10/13/2016] [Indexed: 12/19/2022] Open
Abstract
Parathyroid hormone (PTH) is a primary calcium regulatory hormone. Elevated serum PTH concentrations in primary and secondary hyperparathyroidism have been associated with bone disease, hypertension, and in some studies, cardiovascular mortality. Genetic causes of variation in circulating PTH concentrations are incompletely understood. We performed a genome-wide association study of serum PTH concentrations among 29,155 participants of European ancestry from 13 cohort studies (n=22,653 and n=6502 in discovery and replication analyses, respectively). We evaluated the association of single nucleotide polymorphisms (SNPs) with natural log-transformed PTH concentration adjusted for age, sex, season, study site, and principal components of ancestry. We discovered associations of SNPs from five independent regions with serum PTH concentration, including the strongest association with rs6127099 upstream of CYP24A1 (P=4.2 × 10-53), a gene that encodes the primary catabolic enzyme for 1,25-dihydroxyvitamin D and 25-dihydroxyvitamin D. Each additional copy of the minor allele at this SNP associated with 7% higher serum PTH concentration. The other SNPs associated with serum PTH concentration included rs4074995 within RGS14 (P=6.6 × 10-17), rs219779 adjacent to CLDN14 (P=3.5 × 10-16), rs4443100 near RTDR1 (P=8.7 × 10-9), and rs73186030 near CASR (P=4.8 × 10-8). Of these five SNPs, rs6127099, rs4074995, and rs219779 replicated. Thus, common genetic variants located near genes involved in vitamin D metabolism and calcium and renal phosphate transport associated with differences in circulating PTH concentrations. Future studies could identify the causal variants at these loci, and the clinical and functional relevance of these variants should be pursued.
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Affiliation(s)
- Cassianne Robinson-Cohen
- Division of Nephrology, Department of Medicine, Kidney Research Institute,
- Department of Epidemiology, University of Washington School of Public Health, Seattle, Washington
| | | | - Marcus E Kleber
- Vth Department of Medicine, Mannheim Medical Faculty, Heidelberg University, Mannheim, Germany
| | - Carrie M Nielson
- Department of Public Health and Preventive Medicine, Oregon Health & Science University, Portland, Oregon
| | - Braxton D Mitchell
- Department of Medicine and Program for Personalized and Genomic Medicine, University of Maryland School of Medicine, Baltimore, Maryland
- Geriatric Research and Education Clinical Center, Veterans Administration Medical Center, Baltimore, Maryland
| | - Joshua C Bis
- Cardiovascular Health Research Unit, Department of Medicine, and
| | - Karen M Eny
- Program in Genetics & Genome Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Laura Portas
- Institute of Population Genetics, National Research Council of Italy, Rome, Italy
| | - Joel Eriksson
- Department of Internal Medicine and Clinical Nutrition, Centre for Bone and Arthritis Research, and
| | - Mattias Lorentzon
- Department of Internal Medicine and Clinical Nutrition, Centre for Bone and Arthritis Research, and
| | | | - Yuri Milaneschi
- Department of Psychiatry, EMGO Institute for Health and Care Research and Neuroscience Campus Amsterdam, Vrije Universiteit Medical Center/GGZ inGeest, Amsterdam, The Netherlands
| | - Alexander Teumer
- Institutes for Community Medicine, Department Study of Health in Pomerania - Klinisch-Epidemiologische Forschung (SHIP-KEF), and
| | - Stefan Pilz
- Department of Epidemiology and Biostatistics, EMGO Institute for Health and Care Research, Vrije Universiteit Medical Center, Amsterdam, The Netherlands
- Department of Internal Medicine, Division of Endocrinology and Nuclear Medicine, and
| | - Maria Nethander
- Bioinformatics Core Facility, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Elizabeth Selvin
- Department of Epidemiology, Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Weihong Tang
- Divisions of Epidemiology and Community Health and
| | - Lu-Chen Weng
- Divisions of Epidemiology and Community Health and
| | - Hoi Suen Wong
- Program in Genetics & Genome Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Dongbing Lai
- Departments of Medical and Molecular Genetics and
| | | | | | - Uwe Völker
- Department of Functional Genomics, Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Georg Homuth
- Department of Functional Genomics, Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | | | - Federico Murgia
- Institute of Population Genetics, National Research Council of Italy, Rome, Italy
| | - Jack W Pattee
- Biostatistics, School of Public Health, University of Minnesota, Minneapolis, Minnesota
| | - Eric Orwoll
- Department of Public Health and Preventive Medicine, Oregon Health & Science University, Portland, Oregon
| | - Joseph M Zmuda
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Jose Antonio Riancho
- Department of Medicine, University of Cantabria, and Hospital Universitario Marques de Valdecilla, Insituto de Investigacion Sanitaria, Santander, Spain
| | - Myles Wolf
- Division of Nephrology and Hypertension, Department of Medicine and
- Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Frances Williams
- Department of Twin Research and Genetic Epidemiology, Division of Genetics & Molecular Medicine, King's College, London, United Kingdom
| | - Brenda Penninx
- Department of Psychiatry, EMGO Institute for Health and Care Research and Neuroscience Campus Amsterdam, Vrije Universiteit Medical Center/GGZ inGeest, Amsterdam, The Netherlands
| | - Michael J Econs
- Departments of Medical and Molecular Genetics and
- Medicine, Indiana University, Indianapolis, Indiana
| | - Kathleen A Ryan
- Department of Medicine and Program for Personalized and Genomic Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Claes Ohlsson
- Department of Internal Medicine and Clinical Nutrition, Centre for Bone and Arthritis Research, and
| | - Andrew D Paterson
- Program in Genetics & Genome Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Bruce M Psaty
- Institutes for Community Medicine, Department Study of Health in Pomerania - Klinisch-Epidemiologische Forschung (SHIP-KEF), and
- Departments of Health Services and
- Group Health Research Institute, Group Health Cooperative, Seattle, Washington
| | - David S Siscovick
- Department of Epidemiology, University of Washington School of Public Health, Seattle, Washington
- The New York Academy of Medicine, New York, New York
- Medicine, University of Washington, Seattle, Washington
| | - Jerome I Rotter
- Department of Pediatrics and Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles, Medical Center, Institute for Translational Genomics and Population Sciences, Torrance, California
| | - Mario Pirastu
- Institute of Population Genetics, National Research Council of Italy, Rome, Italy
| | - Elizabeth Streeten
- Department of Medicine and Program for Personalized and Genomic Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Winfried März
- Vth Department of Medicine, Mannheim Medical Faculty, Heidelberg University, Mannheim, Germany
- Synlab Academy, Synlab Services GmbH, Mannheim, Germany; and
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
| | - Caroline Fox
- Department of Genetics and Pharmacogenomics, Merck Research, Whitehouse Station, New Jersey
| | - Josef Coresh
- Department of Epidemiology, Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | | | | | - Ian H de Boer
- Division of Nephrology, Department of Medicine, Kidney Research Institute
- Department of Epidemiology, University of Washington School of Public Health, Seattle, Washington
| | - Bryan Kestenbaum
- Division of Nephrology, Department of Medicine, Kidney Research Institute
- Department of Epidemiology, University of Washington School of Public Health, Seattle, Washington
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9
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Kim ES, Kim SY, Lee JY, Han JH, Sohn TS, Son HS, Moon SD. Identification and functional analysis of a novel CaSR mutation in a family with familial hypocalciuric hypercalcemia. J Bone Miner Metab 2016; 34:662-667. [PMID: 26386835 DOI: 10.1007/s00774-015-0713-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 08/16/2015] [Indexed: 01/09/2023]
Abstract
The calcium-sensing receptor (CaSR) is a G-protein-coupled receptor that plays an essential role in maintaining calcium homeostasis. In the present study, we analyzed the CaSR gene in a Korean family with familial hypocalciuric hypercalcemia (FHH). Genetic studies were performed by direct sequence analysis of the CaSR gene in genomic DNA obtained from peripheral leukocytes. A novel heterozygous G to T substitution at nucleotide position 1711 in exon 6, resulting in the G571W mutation, was identified in the CaSR gene in a 26-year-old female with asymptomatic hypercalcemia, a low calcium/creatinine clearance ratio, and normal intact parathyroid hormone. To study CaSR expression, the mutation was introduced by site-directed mutagenesis into a wild-type (WT) CaSR-expressing pCR3.1 vector, and COS-7 cells were transfected with either the WT or mutant CaSR-containing vector. Transfected cells loaded with Fura-2/AM, a fluorescent indicator of Ca2+, were assessed for CaSR function by the change in intracellular calcium [as measured by the 340 nm/380 nm fluorescence intensity ratio (F340/F380)] made in response to challenge with extracellular Ca2+. Both WT and G571W cells had equivalent amounts of CaSR protein in the cell membrane. However, after challenge with extracellular Ca2+, cells transfected with G571W CaSR responded with a lower F340/F380 ratio than those transfected with WT CaSR and showed decreased sensitivity to extracellular Ca2+ concentrations. The G571W mutation had therefore impaired the CaSR function. In conclusion, we identified a novel loss-of-function mutation, G571W, in the CaSR gene in a Korean family with FHH.
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Affiliation(s)
- Eun Sook Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 56 Dongsoo-ro, Bupyeong-gu, Incheon, 403-720, Republic of Korea
| | - Su Yeon Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 56 Dongsoo-ro, Bupyeong-gu, Incheon, 403-720, Republic of Korea
| | - Ji Young Lee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 56 Dongsoo-ro, Bupyeong-gu, Incheon, 403-720, Republic of Korea
| | - Je Ho Han
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 56 Dongsoo-ro, Bupyeong-gu, Incheon, 403-720, Republic of Korea
| | - Tae Seo Sohn
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Uijungbu St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul, 137-701, Republic of Korea.
| | - Hyun Shik Son
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Uijungbu St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul, 137-701, Republic of Korea
| | - Sung-Dae Moon
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 56 Dongsoo-ro, Bupyeong-gu, Incheon, 403-720, Republic of Korea.
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10
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Papadopoulou A, Gole E, Melachroinou K, Meristoudis C, Siahanidou T, Papadimitriou A. Identification and Functional Characterization of a Calcium-Sensing Receptor Mutation in an Infant with Familial Hypocalciuric Hypercalcemia. J Clin Res Pediatr Endocrinol 2016; 8:341-6. [PMID: 27087013 PMCID: PMC5096500 DOI: 10.4274/jcrpe.2800] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Familial hypocalciuric hypercalcemia (FHH) is an autosomal dominant disorder, associated with inactivating mutations of the calcium-sensing receptor (CaSR). To evaluate the functional significance of a CaSR mutation, identified in a young infant who presented with hypercalcemia and hypocalciuria. The CaSR gene coding sequences were analyzed by polymerase chain reaction amplification and direct sequencing analysis. The mutation identified was introduced by site-directed mutagenesis into a wild-type (WT) CaSR plasmid, and human embryonic kidney 293 T cells were transfected with either the WT or mutant CaSR. The function of the mutated CaSR protein was analyzed by evaluating the free intracellular calcium [(Ca2+)i] response after challenge with extracellular calcium (Ca2+). We identified a heterozygous mutation c.772_773delGTinsA in exon 4 resulting in the substitution of amino acid valine (Val) with amino acid arginine (Arg) and the premature pause of the translation 46 amino acids later (Val258ArgfsTer47). Functional assay showed that cells transfected with the mutant CaSR had a significantly poorer response to extracellular Ca2+ stimulation compared with the WT. We have shown that the c.772_773delGTinsA mutation causes a significant alteration of CaSR function leading to features of FHH in an affected young infant since the first months of life.
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Affiliation(s)
- Anna Papadopoulou
- Athens University Medical School, University General Hospital "Attikon", Third Department of Pediatrics, Athens, Greece, Phone: +30 2105832228 E-mail:
| | - Evangelia Gole
- Athens University Medical School, University General Hospital “Attikon”, Third Department of Pediatrics, Athens, Greece
| | - Katerina Melachroinou
- Biomedical Research Foundation of the Academy of Athens, Division of Basic Neurosciences, Athens, Greece
| | - Christos Meristoudis
- University of Ioannina, Department of Biological Applications and Technology, Ioannina, Greece
| | - Tania Siahanidou
- Athens University Medical School, “Aghia Sophia” Children’s Hospital, First Department of Pediatrics, Athens, Greece
| | - Anastasios Papadimitriou
- Athens University Medical School, University General Hospital “Attikon”, Third Department of Pediatrics, Athens, Greece
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Obermannova B, Sumnik Z, Dusatkova P, Cinek O, Grant M, Lebl J, Hendy GN. Novel calcium-sensing receptor cytoplasmic tail deletion mutation causing autosomal dominant hypocalcemia: molecular and clinical study. Eur J Endocrinol 2016; 174:K1-K11. [PMID: 26764418 DOI: 10.1530/eje-15-1216] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Accepted: 01/12/2016] [Indexed: 01/15/2023]
Abstract
OBJECTIVE Autosomal dominant hypocalcemia (ADH) is a rare disorder caused by activating mutations of the calcium-sensing receptor (CASR). The treatment of ADH patients with 1α-hydroxylated vitamin D derivatives can cause hypercalciuria leading to nephrocalcinosis. DESIGN AND METHODS We studied a girl who presented with hypoparathyroidism and asymptomatic hypocalcemia at age 2.5 years. Mutations of CASR were investigated by DNA sequencing. Functional analyses of mutant and WT CASRs were done in transiently transfected human embryonic kidney (HEK293) cells. RESULTS The proband and her father are heterozygous for an eight-nucleotide deletion c.2703_2710delCCTTGGAG in the CASR encoding the intracellular domain of the protein. Transient expression of CASR constructs in kidney cells in vitro suggested greater cell surface expression of the mutant receptor with a left-shifted extracellular calcium dose-response curve relative to that of the WT receptor consistent with gain of function. Initial treatment of the patient with calcitriol led to increased urinary calcium excretion. Evaluation for mosaicism in the paternal grandparents of the proband was negative. CONCLUSIONS We describe a novel naturally occurring deletion mutation within the CASR that apparently arose de novo in the father of the ADH proband. Functional analysis suggests that the cytoplasmic tail of the CASR contains determinants that regulate the attenuation of signal transduction. Early molecular analysis of the CASR gene in patients with isolated idiopathic hypoparathyroidism is recommended because of its relevance to clinical outcome and treatment choice. In ADH patients, calcium supplementation and low-dose cholecalciferol avoids hypocalcemic symptoms without compromising renal function.
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Affiliation(s)
- Barbora Obermannova
- Department of PediatricsSecond Faculty of Medicine, Charles University in Prague, University Hospital Motol V Uvalu 84, CZ-150 06 Prague, Czech RepublicLady Davis Institute for Medical ResearchSMBD-Jewish General Hospital, McGill University, Montréal, Québec, Canada H3T 1E2Experimental Therapeutics and MetabolismRoom No. EM1.3226 RI-McGill University Health Centre Glen Site, 1001 Décarie Boulevard, Montréal, Québec, Canada H4A 3J1Departments of MedicinePhysiology, and Human Genetics, McGill University, Montréal, Québec, Canada H4A 3J1
| | - Zdenek Sumnik
- Department of PediatricsSecond Faculty of Medicine, Charles University in Prague, University Hospital Motol V Uvalu 84, CZ-150 06 Prague, Czech RepublicLady Davis Institute for Medical ResearchSMBD-Jewish General Hospital, McGill University, Montréal, Québec, Canada H3T 1E2Experimental Therapeutics and MetabolismRoom No. EM1.3226 RI-McGill University Health Centre Glen Site, 1001 Décarie Boulevard, Montréal, Québec, Canada H4A 3J1Departments of MedicinePhysiology, and Human Genetics, McGill University, Montréal, Québec, Canada H4A 3J1
| | - Petra Dusatkova
- Department of PediatricsSecond Faculty of Medicine, Charles University in Prague, University Hospital Motol V Uvalu 84, CZ-150 06 Prague, Czech RepublicLady Davis Institute for Medical ResearchSMBD-Jewish General Hospital, McGill University, Montréal, Québec, Canada H3T 1E2Experimental Therapeutics and MetabolismRoom No. EM1.3226 RI-McGill University Health Centre Glen Site, 1001 Décarie Boulevard, Montréal, Québec, Canada H4A 3J1Departments of MedicinePhysiology, and Human Genetics, McGill University, Montréal, Québec, Canada H4A 3J1
| | - Ondrej Cinek
- Department of PediatricsSecond Faculty of Medicine, Charles University in Prague, University Hospital Motol V Uvalu 84, CZ-150 06 Prague, Czech RepublicLady Davis Institute for Medical ResearchSMBD-Jewish General Hospital, McGill University, Montréal, Québec, Canada H3T 1E2Experimental Therapeutics and MetabolismRoom No. EM1.3226 RI-McGill University Health Centre Glen Site, 1001 Décarie Boulevard, Montréal, Québec, Canada H4A 3J1Departments of MedicinePhysiology, and Human Genetics, McGill University, Montréal, Québec, Canada H4A 3J1
| | - Michael Grant
- Department of PediatricsSecond Faculty of Medicine, Charles University in Prague, University Hospital Motol V Uvalu 84, CZ-150 06 Prague, Czech RepublicLady Davis Institute for Medical ResearchSMBD-Jewish General Hospital, McGill University, Montréal, Québec, Canada H3T 1E2Experimental Therapeutics and MetabolismRoom No. EM1.3226 RI-McGill University Health Centre Glen Site, 1001 Décarie Boulevard, Montréal, Québec, Canada H4A 3J1Departments of MedicinePhysiology, and Human Genetics, McGill University, Montréal, Québec, Canada H4A 3J1
| | - Jan Lebl
- Department of PediatricsSecond Faculty of Medicine, Charles University in Prague, University Hospital Motol V Uvalu 84, CZ-150 06 Prague, Czech RepublicLady Davis Institute for Medical ResearchSMBD-Jewish General Hospital, McGill University, Montréal, Québec, Canada H3T 1E2Experimental Therapeutics and MetabolismRoom No. EM1.3226 RI-McGill University Health Centre Glen Site, 1001 Décarie Boulevard, Montréal, Québec, Canada H4A 3J1Departments of MedicinePhysiology, and Human Genetics, McGill University, Montréal, Québec, Canada H4A 3J1
| | - Geoffrey N Hendy
- Department of PediatricsSecond Faculty of Medicine, Charles University in Prague, University Hospital Motol V Uvalu 84, CZ-150 06 Prague, Czech RepublicLady Davis Institute for Medical ResearchSMBD-Jewish General Hospital, McGill University, Montréal, Québec, Canada H3T 1E2Experimental Therapeutics and MetabolismRoom No. EM1.3226 RI-McGill University Health Centre Glen Site, 1001 Décarie Boulevard, Montréal, Québec, Canada H4A 3J1Departments of MedicinePhysiology, and Human Genetics, McGill University, Montréal, Québec, Canada H4A 3J1 Department of PediatricsSecond Faculty of Medicine, Charles University in Prague, University Hospital Motol V Uvalu 84, CZ-150 06 Prague, Czech RepublicLady Davis Institute for Medical ResearchSMBD-Jewish General Hospital, McGill University, Montréal, Québec, Canada H3T 1E2Experimental Therapeutics and MetabolismRoom No. EM1.3226 RI-McGill University Health Centre Glen Site, 1001 Décarie Boulevard, Montréal, Québec, Canada H4A 3J1Departments of MedicinePhysiology, and Human Genetics, McGill University, Montréal, Québec, Canada H4A 3J1
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Baran N, ter Braak M, Saffrich R, Woelfle J, Schmitz U. Novel activating mutation of human calcium-sensing receptor in a family with autosomal dominant hypocalcaemia. Mol Cell Endocrinol 2015; 407:18-25. [PMID: 25766501 DOI: 10.1016/j.mce.2015.02.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 01/13/2015] [Accepted: 02/19/2015] [Indexed: 12/24/2022]
Abstract
INTRODUCTION Autosomal dominant hypocalcaemia (ADH) is caused by activating mutations in the calcium sensing receptor gene (CaR) and characterised by mostly asymptomatic mild to moderate hypocalcaemia with low, inappropriately serum concentration of PTH. OBJECTIVE The purpose of the present study was to biochemically and functionally characterise a novel mutation of CaR. PATIENTS A female proband presenting with hypocalcaemia was diagnosed to have "idiopathic hypoparathyroidism" at the age of 10 with a history of muscle pain and cramps. Further examinations demonstrated hypocalcaemia in nine additional family members, affecting three generations. MAIN OUTCOME MEASURE P136L CaR mutation was predicted to cause gain of function of CaR. RESULTS Affected family members showed relevant hypocalcaemia (mean ± SD; 1.9 ± 0.1 mmol/l). Patient history included mild seizures and recurrent nephrolithiasis. Genetic analysis confirmed that hypocalcaemia cosegregated with a heterozygous mutation at codon 136 (CCC → CTC/Pro → Leu) in exon 3 of CaR confirming the diagnosis of ADH. For in vitro studies P136L mutant CaR was generated by site-directed mutagenesis and examined in transiently transfected HEK293 cells. Extracellular calcium stimulation of transiently transfected HEK293 cells showed significantly increased intracellular Ca(2+) mobilisation and MAPK activity for mutant P136L CaR compared to wild type CaR. CONCLUSIONS The present study gives insight about a novel activating mutation of CaR and confirms that the novel P136L-CaR mutation is responsible for ADH in this family.
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Affiliation(s)
- Natalia Baran
- Department of Endocrinology and Diabetology, University of Bonn, Sigmund-Freud-Str. 25, 53127 Bonn, Germany; Department of Medicine V, University of Heidelberg, INF 410, 69120 Heidelberg, Germany.
| | - Michael ter Braak
- Institut of Pharmacology, University of Essen, Hufelandstr. 55, 45122 Essen, Germany
| | - Rainer Saffrich
- Department of Medicine V, University of Heidelberg, INF 410, 69120 Heidelberg, Germany
| | - Joachim Woelfle
- Pediatric Endocrinology Division, University of Bonn, Adenauerallee 119, 53113 Bonn, Germany
| | - Udo Schmitz
- Department of Endocrinology and Diabetology, University of Bonn, Sigmund-Freud-Str. 25, 53127 Bonn, Germany
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Gannon AW, Monk HM, Levine MA. Cinacalcet monotherapy in neonatal severe hyperparathyroidism: a case study and review. J Clin Endocrinol Metab 2014; 99:7-11. [PMID: 24203066 PMCID: PMC3879678 DOI: 10.1210/jc.2013-2834] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
CONTEXT Neonatal severe hyperparathyroidism (NSHPT) is a severe form of familial hypocalciuric hypercalcemia characterized by severe hypercalcemia and skeletal demineralization. In most cases, NSHPT is due to biallelic loss-of-function mutations in the CASR gene encoding the calcium-sensing receptor (CaSR), but some patients have heterozygous mutations. Conventional treatment consists of iv saline, bisphosphonates, and parathyroidectomy. OBJECTIVE The aim of this project was to characterize the molecular basis for NSHPT in an affected newborn and to describe the response to monotherapy with cinacalcet. METHODS Clinical and biochemical features were monitored as cinacalcet therapy was initiated and maintained. Genomic DNA was obtained from the proband and parents. The CASR gene was amplified by PCR and sequenced directly. RESULTS The patient was a full-term male who developed hypotonia and respiratory failure soon after birth. He was found to have multiple fractures and diffuse bone demineralization, with a marked elevation in serum ionized calcium (1.99 mmol/L) and elevated serum levels of intact PTH (1154 pg/mL); serum 25-hydroxyvitamin D was low, and fractional excretion of calcium was reduced. The serum calcium level was not reduced by iv saline infusion. Based on an extensive family history of autosomal dominant hypercalcemia, a diagnosis of NSHPT was made, and cinacalcet therapy was initiated with a robust and durable effect. Molecular studies revealed a heterozygous R185Q missense mutation in the CASR in the patient and his father, whereas normal sequences for the CASR gene were present in the patient's mother. CONCLUSIONS We describe the first use of cinacalcet as monotherapy for severe hypercalcemia in a newborn with NSHPT. The rapid and durable response to cinacalcet suggests that a trial of calcimimetic therapy should be considered early in the course of NSHPT.
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Affiliation(s)
- Anthony W Gannon
- Division of Endocrinology and Diabetes (A.W.G., M.A.L.), and Department of Pharmacy Services (H.M.M.), The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104; and Department of Pediatrics (A.W.G., M.A.L.), University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104
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Liu G, Neumeister M, Reichensperger J, Yang RD. Therapeutic potential of human adipose stem cells in a cancer stem cell-like gastric cancer cell model. Int J Oncol 2013; 43:1301-9. [PMID: 23900519 DOI: 10.3892/ijo.2013.2039] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 06/03/2013] [Indexed: 11/05/2022] Open
Abstract
Cancer stem cells (CSCs) or circulating tumor cells play an important role in tumor initiation, invasion, metastasis and resistance to anticancer therapies. Therapies that target gastric tumor CSCs have potential clinical application for preventing malignant gastric tumor progression and metastasis. We isolated CD44+ gastric cancer cells from the gastric cancer cell line AGS and Hs746T cells and maintained the cells in a novel stem cell culture. The cells were kept in an undifferentiated proliferative state and we characterized their cancer stem cell properties and chemotherapy-resistance behavior. The CD44+ cancer cells were also co-cultured with human adipose stem cells (ADSCs) to determine the chemotherapy-promotion effects of the adipose cells on the CD44+ cancer cells. The CD44+ gastric cancer cell model is a non-adhesion, 3-dimensional, spheroid phenotype. The non-adherent CD44+ cells have cancer stem cell properties and are highly chemo-resistant. However, these cells regained chemo-sensitivity when re-attached to an extracellular matrix-coated attachment surface. The human adipose stem cells significantly promoted the chemo-sensitivity of the non-adherent CD44+ gastric cancer cells. Integrin α2/β2 and the Wnt signaling pathways are involved in the mechanisms. We concluded that the in vitro non-adherent CD44+ gastric cancer cell model resembles the circulating gastric tumor cells in vivo. Introduction of an appropriate attachment surface significantly promotes chemo-sensitivity of the non-adherent CD44+ gastric cancer cells. The human adipose stem cells function as a 'living vehicle surface' for such a purpose in vivo.
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Affiliation(s)
- Guangming Liu
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Southern Illinois University School of Medicine, Springfield, IL 62794, USA
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Hendy GN, Canaff L, Cole DEC. The CASR gene: alternative splicing and transcriptional control, and calcium-sensing receptor (CaSR) protein: structure and ligand binding sites. Best Pract Res Clin Endocrinol Metab 2013; 27:285-301. [PMID: 23856260 DOI: 10.1016/j.beem.2013.02.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The calcium-sensing receptor (CaSR) is a G protein-coupled receptor encoded by a single copy gene. The human CASR gene spans ~103-kb and has eight exons. Promoters P1 and P2 drive transcription of exons 1A and 1B, respectively, encoding alternative 5'-UTRs that splice to exon 2 encoding the common part of the 5'-UTR. Exons 2-7 encode the CaSR protein of 1078 amino acids. Functional elements responsive to 1,25-dihydroxyvitamin D, proinflammatory cytokines, and glial cells missing-2 are present in the CASR promoters. Evolutionarily, the exon structure, first seen in aquatic vertebrates, is well-conserved with a single linkage disequilibrium haplotype block for protein coding exons 2-7. Structural features of the human CaSR protein are: an N-terminal signal peptide (19 amino acids (aa)); an extracellular domain (~600 aa) having a bi-lobed Venus Flytrap (VFT) domain with several Ca(2+)-binding sites; and a nine-cysteines domain that transduces the activation signal to the 7-transmembrane domain (250 aa) and the C-terminal tail (216 aa).
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Affiliation(s)
- Geoffrey N Hendy
- Calcium Research Laboratory, and Hormones and Cancer Research Unit, Royal Victoria Hospital and McGill University Health Centre, Montreal, QC H3A 1A1, Canada.
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Lia-Baldini AS, Magdelaine C, Nizou A, Airault C, Salles JP, Moulin P, Delemer B, Aitouares M, Funalot B, Sturtz F, Lienhardt-Roussie A. Two novel mutations of the calcium-sensing receptor gene affecting the same amino acid position lead to opposite phenotypes and reveal the importance of p.N802 on receptor activity. Eur J Endocrinol 2013; 168:K27-34. [PMID: 23169696 DOI: 10.1530/eje-12-0714] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
OBJECTIVE Gain-of-function mutations of the calcium-sensing receptor (CASR) gene have been identified in patients with sporadic or familial autosomal dominant hypocalcemia (ADH). Inactivating mutations of the CASR gene cause familial hypocalciuric hypercalcemia (FHH). Here, we report two novel CASR mutations affecting the same amino acid (p.N802); one causes ADH and the other atypical FHH. PATIENTS AND METHODS The first patient, an 11-year-old girl suffering from hypocalcemia, developed nephrocalcinosis when she was only 5 years old. The second patient is a 30-year-old woman who presented with mild hypercalcemia. PCR amplification of CASR coding exons and direct sequencing of PCR products were used to identify mutations. Site-directed mutagenesis was used to generate mutated CASR cDNAs in an expression plasmid. Using the MAPK assay system and transient transfection of Cos-7 cells with wild-type (WT) and mutated CASR, we studied the responses of these mutated receptors to extracellular Ca(2+) and to the negative allosteric CASR modulator, NPS2143. RESULTS Two heterozygous missense mutations (p.N802I and p.N802S) affecting a residue in the sixth transmembrane domain of CASR were identified. In functional tests, the response of the p.N802S mutant to calcium was typical of an inactivating mutation. However, the p.N802I mutant had 70% of the maximally stimulated WT receptor activity even in the absence of extracellular calcium. This constitutive activity was only partially inhibited by the inhibitor, NPS2143. CONCLUSIONS The asparagine at amino acid position 802 appears to be essential for the activity of the CASR protein and is implicated in the mechanism of CASR signaling.
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Affiliation(s)
- Anne-Sophie Lia-Baldini
- EA 6309 - Maintenance Myélinique et Neuropathies Périphériques, Faculté de Médecine - Biochimie, Université de Limoges, 6ème étage, 2 rue du Dr Marcland, 87025 Limoges, France.
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Tonyushkina KN, O'Connor S, Dunbar NS. A novel CaSR mutation presenting as a severe case of neonatal familial hypocalciuric hypercalcemia. INTERNATIONAL JOURNAL OF PEDIATRIC ENDOCRINOLOGY 2012; 2012:13. [PMID: 22620673 PMCID: PMC3465174 DOI: 10.1186/1687-9856-2012-13] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 05/23/2012] [Indexed: 12/30/2022]
Abstract
BACKGROUND Familial Hypocalciuric Hypercalcemia (FHH) is a generally benign disorder caused by heterozygous inactivating mutations in the Calcium-Sensing Receptor (CaSR) gene resulting in altered calcium metabolism. OBJECTIVE We report a case of unusually severe neonatal FHH due to a novel CaSR gene mutation that presented with perinatal fractures and moderate hypercalcemia. CASE OVERVIEW: A female infant was admitted at 2 weeks of age for suspected non-accidental trauma (NAT). Laboratory testing revealed hypercalcemia (3.08 mmol/L), elevated iPTH (20.4 pmol/L) and low urinary calcium clearance (0.0004). Radiographs demonstrated multiple healing metaphyseal and rib fractures and bilateral femoral bowing. The femoral deformity and stage of healing were consistent with prenatal injuries rather than non-accidental trauma (NAT). Treatment was initiated with cholecalciferol, 400 IU/day, and by 6 weeks of age, iPTH levels had decreased into the high-normal range. Follow up radiographs demonstrated marked improvement of bone lesions by 3 months. A CaSR gene mutation study showed heterozygosity for a T>C nucleotide substitution at c.1664 in exon 6, resulting in amino acid change I555T in the extracellular domain consistent with a missense mutation. Her mother does not carry the mutation and the father is unknown. At 18 months of age, the child continues to have relative hyperparathyroidism and moderate hypercalcemia but is otherwise normal. CONCLUSION This neonate with intrauterine fractures and demineralization, moderate hypercalcemia and hyperparathyroidism was found to have a novel inactivating missense mutation of the CaSR not detected in her mother. Resolution of bone lesions and reduction of hyperparathyroidism was likely attributable to the natural evolution of the disorder in infancy as well as the mitigating effect of cholecalciferol treatment.
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Affiliation(s)
- Ksenia N Tonyushkina
- Baystate Children's Hospital, Tufts University School of Medicine, 759 Chestnut St, Dept of Pediatrics, Springfield, MA 01199, USA.
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Christensen SE, Nissen PH, Vestergaard P, Mosekilde L. Familial hypocalciuric hypercalcaemia: a review. Curr Opin Endocrinol Diabetes Obes 2011; 18:359-70. [PMID: 21986511 DOI: 10.1097/med.0b013e32834c3c7c] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PURPOSE OF REVIEW Hypercalcaemia is a potentially life-threatening condition. Familial hypocalciuric hypercalcaemia (FHH) is a rare, lifelong, benign condition. It is important to separate this condition from other hypercalcaemic states such as hypercalcaemia of malignancy and primary hyperparathyroidism (PHPT). RECENT FINDINGS FHH is caused by inactivating mutations in the calcium sensing receptor (CASR) gene leading to a general calcium-hyposensitivity, compensatory hypercalcaemia and hypocalciuria. The inheritance of FHH is autosomal dominant. Similar to PHPT, FHH is characterized by hypercalcaemia, unsuppressed or elevated plasma parathyroid hormone, and typically normal renal function. The phenotype is normal, and hypercalcaemic symptoms are generally absent. The hallmark is a relatively low urine calcium excretion in contrast to PHPT, in which urine calcium excretion is increased. The vitamin D status as measured by plasma 25-hydroxyvitamin D has been reported to be normal with normal seasonal variations, whereas plasma 1,25-dihydroxyvitamin D has been found slightly increased compared to normal. Bone mineral density Z-scores are normal in spite of a slightly increased bone turnover. Differential diagnoses include mainly PHPT, but in some cases also hypercalcaemia of malignancy and use of thiazide diuretics. SUMMARY In general, FHH does not require treatment. We recommend a two-step diagnostic procedure. First, the calcium/creatinine clearance ratio is measured from a 24-h urine. Second, all patients with calcium/creatinine clearance ratio of 0.020 or less are tested for mutations in the CASR gene. The diagnostic sensitivity of this setup is 98%.
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Affiliation(s)
- Signe E Christensen
- Department of Medicine and Endocrinology, Aarhus University Hospital, Aarhus C, Denmark.
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Rodrigues LS, Cáu ACA, Bussmann LZ, Bastida G, Brunetto OH, Corrêa PHS, Martin RM. New mutation in the CASR gene in a family with familial hypocalciuric hypercalcemia (FHH) and neonatal severe hyperparathyroidism (NSHPT). ACTA ACUST UNITED AC 2011; 55:67-71. [PMID: 21468522 DOI: 10.1590/s0004-27302011000100009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2010] [Accepted: 01/19/2011] [Indexed: 01/20/2023]
Abstract
A loss of calcium-sensing receptor (CASR) function due to inactivating mutations can cause familial hypocalciuric hypercalcemia (FHH) or neonatal severe hyperparathyroidism (NSHPT). NSHPT represents the most severe expression of FHH and courses as a life-threatening condition. The aim of this study was to identify and characterize a CASR mutation in a female infant brought to the health service due to dehydration, apathy, lack of breast feeding and severe hypercalcemia. Molecular analysis was performed on genomic DNA of the index case and her parents. A novel homozygous mutation (p.E519X) in CASR was identified in the proband; both mother and father had the same mutation in heterozygous state, confirming their FHH condition. The mutation results in a truncated and inactive protein due to the lack of transmembrane and intracellular domains. The identification of this novel CASR gene mutation established the basis of hypercalcemia in this family and allowed a genetic counseling.
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Affiliation(s)
- Luiza Souza Rodrigues
- Laboratory of Molecular Genetics and Hormones, Division of Endocrinology, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brazil
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Al-Salameh A, Cetani F, Pardi E, Vulpoi C, Pierre P, de Calan L, Guyetant S, Jeunemaitre X, Lecomte P. A novel mutation in the calcium-sensing receptor in a French family with familial hypocalciuric hypercalcaemia. Eur J Endocrinol 2011; 165:359-63. [PMID: 21566075 DOI: 10.1530/eje-11-0141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
OBJECTIVE The calcium-sensing receptor (CASR) has an important role in calcium homoeostasis by controlling PTH secretion and renal calcium handling. Inactivating mutations in the CASR gene (HGNC ID: 1514) cause familial hypocalciuric hypercalcaemia (FHH). We present a case of FHH patient to describe a novel mutation in the CASR. SUBJECTS AND METHODS A 34-year-old patient was referred because of recurrent hypercalcaemia after resection of two hyperplastic parathyroids. Extensive evaluation found elevated PTH and low calcium/creatinine clearance ratio. One of her three children had high serum calcium concentrations. Genetic studies were performed by PCR amplification of CASR coding exons and direct sequencing of PCR products. Transient transfection of the wild-type (WT) CASR and the mutant CASR into COS-7 was performed to assess functional impact of the mutation and the capacity of either protein to mediate increases in cellular levels of inositol phosphates (IPs). RESULTS CASR sequencing found a previously undescribed heterozygous base substitution, determining a change of threonine to isoleucine at codon 550 (p.T550I) in the sixth exon. In contrast to those transfected with WT CASR, which showed a five- to eightfold increase in total IPs at high levels of calcium, COS-7 cells transfected with the (p.T550I) mutant showed no increase confirming to the inactivating nature of the mutation. COS-7 cells co-transfected with the WT and the (p.T550I) mutant showed an intermediate response suggesting a possible dominant negative effect. CONCLUSION This case report presents a not-yet-described mutation in the cysteine-rich region of the CASR extracellular domain, a mutation with a possible dominant negative effect.
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Affiliation(s)
- Abdallah Al-Salameh
- Department of Endocrinology, CHRU Bretonneau, University Hospital of Tours, 2 Bis Boulevard Tonnellé, 37044 Tours Cedex 9, France
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Livadariu E, Auriemma RS, Rydlewski C, Vandeva S, Hamoir E, Burlacu MC, Maweja S, Thonnard AS, Betea D, Vassart G, Daly AF, Beckers A. Mutations of calcium-sensing receptor gene: two novel mutations and overview of impact on calcium homeostasis. Eur J Endocrinol 2011; 165:353-8. [PMID: 21566074 DOI: 10.1530/eje-11-0121] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Genetic disorders of calcium metabolism arise in a familial or sporadic setting. The calcium-sensing receptor (CASR) plays a key role in maintaining calcium homeostasis and study of the CASR gene can be clinically useful in determining etiology and appropriate therapeutic approaches. We report two cases of novel CASR gene mutations that illustrate the varying clinical presentations and discuss these in terms of the current understanding of CASR function. PATIENTS AND METHODS A 16-year-old patient had mild hypercalcemia associated with low-normal urinary calcium excretion and normal-to-high parathyroid hormone (PTH) levels. Because of negative family history, familial hypocalciuric hypercalcemia was originally excluded. The second patient was a 54-year-old man with symptomatic hypocalcemia, hyperphosphatemia, low PTH, and mild hypercalciuria. Familial investigation revealed the same phenotype in the patient's sister. The coding region of the CASR gene was sequenced in both probands and their available first-degree relatives. RESULTS The first patient had a novel heterozygous inactivating CASR mutation in exon 4, which predicted a p.A423K change; genetic analysis was negative in the parents. The second patient had a novel heterozygous activating CASR mutation in exon 6, which predicted a p.E556K change; the affected sister of the proband was also positive. CONCLUSIONS We reported two novel heterozygous mutations of the CASR gene, an inactivating mutation in exon 4 and the first activating mutation reported to date in exon 6. These cases illustrate the importance of genetic testing of CASR gene to aid correct diagnosis and to assist in clinical management.
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Affiliation(s)
- Elena Livadariu
- Department of Endocrinology, Centre Hospitalier Universitaire de Liège, University of Liège, 4000 Liège, Belgium
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Fernández López I, Fernández Peña I, Cózar León MV, Viloria Peñas MM, Martínez De Pinillos Gordillo G, Fernández-Ladreda MT, Duran García S. [Usefulness of genetic tests in familial hypocalciuric hypercalcemia with atypical clinical presentation]. ACTA ACUST UNITED AC 2011; 58:325-30. [PMID: 21697018 DOI: 10.1016/j.endonu.2011.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 04/07/2011] [Accepted: 04/17/2011] [Indexed: 11/18/2022]
Abstract
OBJECTIVES Biochemical tests related to calcium and phosphorus metabolism have traditionally been considered as a reliable tool to differentiate familial hypocalciuric hypercalcemia (FHH) from primary hyperparathyroidism (PHPT). However, diagnosis may sometimes be difficult even for experienced clinicians. Our objective was to assess the accuracy of diagnostic tests in FHH and the circumstances in which genetic studies are required. PATIENTS AND METHODS A descriptive study was conducted of two families with hypercalcemia and suspected atypical FHH. Urinary calcium excretion was measured in 24-hour urine using different tests (calcium excretion (CE), urinary calcium/creatinine clearance ratio (UCCR)), and serum PTH and 25-hydroxyvitamin D levels were tested. Index cases underwent genetic study. RESULTS One patient from the first family showed overt, persistent hypercalciuria with values more consistent with PHPT than with FHH if we consider, as proposed by guidelines, a UCCR lower than 0.01 as diagnostic of FHH and a value higher than 0.02 as diagnostic of PHPT. The index case of the second family underwent surgery for a parathyroid adenoma. Both cases had a mutation c. 164C>T (Pro55Leu) in exon 2 in heterozygosis. CONCLUSIONS According to current clinical guidelines, definitive diagnosis of FHH requires genetic confirmation, which allowed in our case for detection of two families with FHH and atypical clinical presentations. We think that rational use of genetic tests may avoid unnecessary surgery and excess monitoring costs.
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Affiliation(s)
- Ignacio Fernández López
- Unidad de Gestión Clínica, Endocrinología y Nutrición, Hospital Universitario Virgen de Valme, Sevilla, España.
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Neonatal severe hyperparathyroidism: further clinical and molecular delineation. Eur J Pediatr 2011; 170:625-31. [PMID: 20972686 DOI: 10.1007/s00431-010-1335-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Accepted: 10/11/2010] [Indexed: 01/03/2023]
Abstract
UNLABELLED We report a newborn female from a consanguineous Sri Lankan family with clinical and biochemical features of neonatal severe hyperparathyroidism (NSHPT). Mutation screening of the calcium-sensing receptor (CASR) gene in genomic DNA revealed a homozygous truncating mutation (c.679C>T, predicting p.R227X), confirming the clinical diagnosis. Other mutations at the R227 position are reported to cause varying degrees of hypercalcemia and hyperparathyroidism, but this nonsense variant is novel and expected to induce unremitting hyperparathyroidism from birth onward. In our patient with NSHPT, early bisphosphonate therapy was crucial in counteracting the marked hypercalcemia and allowed for safe surgical intervention ("total" parathyroidectomy, "thymectomy and hemithyroidectomy") at 3 months of age. CONCLUSION This report highlights the continuing challenges in diagnosis and management of this life-threatening condition.
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Reh CMS, Hendy GN, Cole DEC, Jeandron DD. Neonatal hyperparathyroidism with a heterozygous calcium-sensing receptor (CASR) R185Q mutation: clinical benefit from cinacalcet. J Clin Endocrinol Metab 2011; 96:E707-12. [PMID: 21289269 DOI: 10.1210/jc.2010-1306] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
UNLABELLED Neonatal hyperparathyroidism can be caused by a heterozygous inactivating mutation in the calcium-sensing receptor. Calcimimetics, allosteric activators of the calcium-sensing receptor, may provide an effective means of reducing PTH secretion in such patients. OBJECTIVE/PATIENT: The objective of the study was to identify the molecular defect and to monitor the postnatal course of a 1-wk-old infant with elevated blood ionized calcium, serum PTH, and alkaline phosphatase and low calcium excretion. The parents were normocalcemic. METHODS CASR gene mutation analysis was performed on genomic DNA of the proband and her parents. The infant was treated initially with pamidronate and then cinacalcet. RESULTS A heterozygous mutation (R185Q, CGA > CAA) in exon 4 of the CASR gene was identified in the proband. The CASR gene of both parents was normal. At 1 wk of age, iv fluids and furosemide were initiated, but hypercalcemia, hyperparathyroidism, and low calcium excretion persisted. At 2 wk of age, a single iv dose of pamidronate resulted in hypocalcemia and further increase in PTH levels, but hypercalcemia recurred within 1 wk. At 3 wk of age, a single oral dose of cinacalcet resulted in decreased PTH levels at 2 h; blood-ionized calcium reached a nadir at 10 h. Three days later daily cinacalcet was initiated, resulting in normalization of ionized calcium. The suppression of serum PTH and reduction in total serum calcium was maintained long term. CONCLUSIONS In neonatal hyperparathyroidism secondary to presumed de novo heterozygous CASR mutation, treatment with cinacalcet decreases PTH secretion and serum calcium levels and mitigates the need for parathyroidectomy.
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Affiliation(s)
- Christina M S Reh
- The Center for Endocrinology, Diabetes, and Metabolism at Children's Hospital Los Angeles, Keck School of Medicine of University of Southern California, Los Angeles, California 90027, USA
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BRCA1 suppresses the expression of survivin and promotes sensitivity to paclitaxel through the calcium sensing receptor (CaSR) in human breast cancer cells. Cell Calcium 2011; 49:79-88. [DOI: 10.1016/j.ceca.2011.01.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 01/07/2011] [Accepted: 01/12/2011] [Indexed: 01/09/2023]
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Elamin WF, de Buyl O. A novel mutation in the calcium-sensing receptor gene in an Irish pedigree showing familial hypocalciuric hypercalcemia: a case report. J Med Case Rep 2010; 4:349. [PMID: 21034470 PMCID: PMC2987963 DOI: 10.1186/1752-1947-4-349] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Accepted: 10/29/2010] [Indexed: 01/01/2023] Open
Abstract
Introduction Familial hypocalciuric hypercalcemia is a rare autosomal dominant disorder characterized by asymptomatic and non-progressive hypercalcemia due to mutations of the calcium-sensing receptor gene. Disorders of calcium metabolism are very common in the elderly, and they can coexist with familial hypocalciuric hypercalcemia in affected families. Case presentation We describe an Irish family with hypercalcemia and hypocalciuria. The proband, an 80-year-old Irish woman, presented with hypercalcemia, relative hypocalciuria, and an elevated parathormone level. She also had chronic kidney disease stage 3 and vitamin D deficiency. Two of her sons were also found to be hypercalcemic and hypocalciuric. DNA sequencing identified a novel missense inactivating mutation in the calcium sensing-receptor gene of the proband and her two hypercalcemic sons. Conclusion Familial hypocalciuric hypercalcemia due to a novel mutation in the calcium-sensing receptor gene was diagnosed in the proband and her two sons. Disorders of calcium metabolism can be multifarious in the elderly. We suggest that testing first degree relatives for calcium levels and DNA sequencing may have a role in the assessment of elderly patients with parathormone-related hypercalcemia.
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Guarnieri V, Canaff L, Yun FHJ, Scillitani A, Battista C, Muscarella LA, Wong BYL, Notarangelo A, D'Agruma L, Sacco M, Cole DEC, Hendy GN. Calcium-sensing receptor (CASR) mutations in hypercalcemic states: studies from a single endocrine clinic over three years. J Clin Endocrinol Metab 2010; 95:1819-29. [PMID: 20164288 DOI: 10.1210/jc.2008-2430] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
CONTEXT Inactivating mutations of the calcium-sensing receptor (CASR) are implicated in different hypercalcemic syndromes, including familial hypocalciuric hypercalcemia (FHH), primary hyperparathyroidism (PHPT), and familial isolated hyperparathyroidism (FIHP). However, molecular diagnostics applied to large nonselected hypercalcemic cohorts from a single center have not been reported. OBJECTIVE Our objective was to describe the prevalence, type, and potential pathogenicity of CASR mutations in a series of cases with FHH (n = 17), PHPT (n = 165), and FIHP (n = 3) and controls (n = 198) presenting at a single endocrine clinic. SUBJECTS All were prospectively evaluated at the "Casa Sollievo della Sofferenza" Hospital in southern Italy over a 3-yr period. METHODS CASR screening was conducted by denaturing HPLC. The variant CASRs were functionally characterized by transient transfection studies in kidney cells in vitro. RESULTS A single novel missense variant was identified in one PHPT case. However, in FHH probands, mutations were found in eight of 17 (47%). With a hypercalcemic family member, mutation detection rate in FHH rose to seven of eight (87%), whereas only one of nine sporadic cases was positive, and none of the three FIHP cases had detectable CASR mutations. Five missense variant CASRs, identified in control subjects, performed as wild type in functional assays, whereas the missense mutant CASRs identified in the FHH patients, and in the one PHPT case, exhibited significant impairment. A novel intronic mutation (IVS4-19a-->c) found in one FHH family, created an abnormally spliced product in an in vitro minigene assay. CONCLUSION CASR testing, with functional analysis, provides critical confirmatory evidence in the differential diagnosis of hypercalcemic states.
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Affiliation(s)
- Vito Guarnieri
- Departments of Laboratory Medicine and Pathobiology, University of Toronto, Ontario, Canada M5G 1L5
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Liu G, Hu X, Chakrabarty S. Vitamin D mediates its action in human colon carcinoma cells in a calcium-sensing receptor-dependent manner: downregulates malignant cell behavior and the expression of thymidylate synthase and survivin and promotes cellular sensitivity to 5-FU. Int J Cancer 2010; 126:631-9. [PMID: 19621386 DOI: 10.1002/ijc.24762] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Vitamin D (VD) protects against colon carcinogenesis by mechanisms not fully understood. We had earlier reported on the similarity in the biologic action of VD and that of the calcium-sensing receptor (CaSR) in human colon carcinoma cells. At the molecular level, the CaSR gene contains 2 VD response elements and VD stimulates the expression of CaSR. In this study, we investigated on the relationship between VD action and CaSR function. We determined and compared the action of VD in human colon carcinoma cells (CBS, Moser, Caco-2 and HCT116) and their CaSR knocked-down counterparts. VD inhibited cellular proliferation, cellular invasion, and anchorage-independent growth and stimulated the expression of p21/Waf1 but not in CaSR knocked-down cells. These results demonstrate, for the first time, that the known tumor-suppressive function of VD requires functional CaSR and knocking down CaSR expression abrogated this function of VD. We recently reported that activation of CaSR in human colon carcinoma cells downregulated the expression of thymidylate synthase (TS) and survivin and promoted a significant increase in sensitivity to cytotoxic drugs. We now demonstrate, for the first time, that VD suppressed the expression of TS and survivin, TS and survivin gene transcriptional activities and promoted a cytotoxic response to 5-FU in a CaSR-dependent manner. Ectopic expression of wild-type CaSR in colon carcinoma cells also inhibited the expression of TS and survivin and enhanced cellular sensitivity to 5-FU. VD, however, could no longer enhance cellular sensitivity to 5-FU in cells overexpressing CaSR.
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Affiliation(s)
- Guangming Liu
- Department of Microbiology, Immunology and Cell Biology, Southern Illinois University School of Medicine, Springfield, IL 62794-9677, USA
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Nanjo K, Nagai S, Shimizu C, Tajima T, Kondo T, Miyoshi H, Yoshioka N, Koike T. Identification and functional analysis of novel calcium-sensing receptor gene mutation in familial hypocalciuric hypercalcemia. Endocr J 2010; 57:787-92. [PMID: 20697181 DOI: 10.1507/endocrj.k10e-178] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Familial hypocalciuric hypercalcemia (FHH) is a benign disorder with heterozygous inactivating mutations in the calcium-sensing receptor (CASR) gene. The present study describes the identification and functional analysis of a novel CASR gene mutation leading to FHH. The proband is a 33-yr-old woman (Ca 11.0 mg/dL, intact-PTH 68 pg/mL, FECa 0.17 %). Leukocyte DNA was isolated in four family members and a novel heterozygous mutation (D190G, GAT>GGT) in exon 4 of CASR gene was identified by direct sequence analysis. The mutant CASR expression vector was constructed by mutagenesis procedure and its response to Ca(2+) was characterized by transient transfection into human embryonic kidney (HEK) 293 cells and treatment with increasing extracellular Ca(2+) concentrations. HEK cells didn't activate intracellular signaling (MAPK activation) in response to increases of extracellular Ca(2+) concentrations when the mutant receptor was expressed normally at the cell surface. The novel heterozygous mutation (D190G) identified in the present study showed that the reduction of activity of CASR to extracellular Ca(2+) caused FHH in patients and our study demonstrated the importance of Asp-190 participated in response to Ca(2+) in CASR.
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Affiliation(s)
- Kazuhiro Nanjo
- Department of Medicine II, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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Lu JYL, Yang Y, Gnacadja G, Christopoulos A, Reagan JD. Effect of the Calcimimetic R-568 [3-(2-Chlorophenyl)-N-((1R)-1-(3-methoxyphenyl)ethyl)-1-propanamine] on Correcting Inactivating Mutations in the Human Calcium-Sensing Receptor. J Pharmacol Exp Ther 2009; 331:775-86. [DOI: 10.1124/jpet.109.159228] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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Unusually severe phenotype of neonatal primary hyperparathyroidism due to a heterozygous inactivating mutation in the CASR gene. Eur J Pediatr 2009; 168:569-73. [PMID: 18751724 DOI: 10.1007/s00431-008-0794-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Accepted: 07/01/2008] [Indexed: 12/30/2022]
Abstract
We present a male patient with neonatal severe primary hyperparathyroidism, whose manifestation was exceptionally serious for the heterozygous inactivating mutation he carried in the CASR gene. The patient presented soon after birth with respiratory distress requiring long-term mechanical ventilation, bone and chest deformities, feeding problems, and hypotonia. He had hypercalcaemia, hypophosphataemia, and hyperparathyroidism. There was no known history of calcium metabolism disorders in the family. As the impact on calcaemia of a rescue therapy with bisphosphonates was only transient, a subtotal and subsequently total parathyroidectomy were performed in the fourth month of life. Afterwards his clinical status improved and the fractures healed, but his neuropsychological development is delayed due to cerebral atrophy. Genetic analysis revealed a heterozygous missense CASR mutation R185Q, and an approximately equal expression of the mutated and wild-type RNA in the parathyroid tissue. The mother of the child was homozygous for the wild-type allele; the father is unknown. In conclusion, this patient demonstrates how serious neonatal hyperparathyroidism can be when caused by a heterozygous mutation. This may be attributable to a combination of dominant-negative action of the mutant allele with an intrauterine foetal hyperparathyroidism developed in the mother's normocalcaemic environment, further aggravated by a putative maternal vitamin D deficiency during pregnancy.
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Hendy GN, Guarnieri V, Canaff L. Chapter 3 Calcium-Sensing Receptor and Associated Diseases. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2009; 89:31-95. [DOI: 10.1016/s1877-1173(09)89003-0] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Rus R, Haag C, Bumke-Vogt C, Bähr V, Mayr B, Möhlig M, Schulze E, Frank-Raue K, Raue F, Schöfl C. Novel inactivating mutations of the calcium-sensing receptor: the calcimimetic NPS R-568 improves signal transduction of mutant receptors. J Clin Endocrinol Metab 2008; 93:4797-803. [PMID: 18796518 DOI: 10.1210/jc.2008-1076] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
CONTEXT AND OBJECTIVE Inactivating mutations in the calcium-sensing receptor (CaSR) gene cause neonatal severe hyperparathyroidism and familial hypocalciuric hypercalcemia (FHH). The aims of the present study were the functional characterization of novel mutations of the CaSR found in FHH patients, the comparison of in vitro receptor function with clinical parameters, and the effect of the allosteric calcimimetic NPS R-568 on the signaling of mutant receptors. METHODS Wild-type and mutant CaSRs (W530G, C568Y, W718X, M734R, L849P, Q926R, and D1005N) were expressed in human embryonic kidney 293 cells. Receptor signaling was studied by measuring intracellular free calcium in response to different concentrations of extracellular calcium ([Ca(2+)](o)). RESULTS Four CaSR mutations (C568Y, W718X, M734R, and L849P) demonstrated a complete lack of a [Ca(2+)](o)-induced cytosolic Ca(2+) response up to 30 mm [Ca(2+)](o), whereas the CaSR mutants W530G, Q926R, and D1005N retained some sensitivity to [Ca(2+)](o). There was no significant relation between the in vitro calcium sensitivity, serum calcium, and intact PTH levels in the patients. Patients with C-terminal CaSR mutations had a calcium to creatine ratio above the established diagnostic threshold of 0.01 for FHH. The calcimimetic NPS R-568 enhanced the responsiveness to [Ca(2+)](o) in CaSR mutants of the extracellular domain (W530G and C568Y) as well as the intracellular C-terminal domain (Q926R and D1005N). CONCLUSION Therefore, calcimimetics might offer medical treatment for symptomatic FHH patients, and more important, for patients with neonatal severe hyperparathyroidism that harbor calcimimetic-sensitive CaSR mutants.
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Affiliation(s)
- Ramona Rus
- Division of Neuroendocrinology, Department of Neurosurgery, Friedrich-Alexander University Erlangen-Nuremberg, Schwabachanlage 6, 91054 Erlangen, Germany
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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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