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Mogl MT, Goretzki PE. [Special features of the diagnostics and treatment of hereditary primary hyperparathyroidism]. CHIRURGIE (HEIDELBERG, GERMANY) 2023:10.1007/s00104-023-01897-8. [PMID: 37291366 DOI: 10.1007/s00104-023-01897-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/08/2023] [Indexed: 06/10/2023]
Abstract
Between 2% and 10% of patients with primary hyperparathyroidism (pHPT) are diagnosed with hereditary forms of primary hyperparathyroidism (hpHPT). They are more prevalent in younger patients before the age of 40 years, in patients with persistence or recurrence of pHPT and pHPT patients with multi-glandular disease (MGD). The various forms of hpHPT diseases can be classified into four syndromes, i.e., hpHPT associated with diseases of other organ systems, and four diseases that are confined to the parathyroid glands. Approximately 40% of patients with hpHPT suffer from multiple endocrine neoplasia type 1 (MEN-1) or show germline mutations of the MEN‑1 gene. Currently, germline mutations that lead to a specific diagnosis in patients with hpHPT have currently been described in 13 different genes, which enables a clear diagnosis of the disease; however, a clear genotype-phenotype correlation does not exist, even though the complete loss of a coded protein (e.g. due to frame-shift mutations in the calcium sensing receptor, CASR) often leads to more severe clinical consequences than merely a reduced function of the protein (e.g. due to point mutation). As the various hpHPT diseases require different treatment approaches, which do not correspond to that of sporadic pHPT, a clear definition of the specific form of hpHPT must always be strived for. Therefore, before surgery of a pHPT with clinical, imaging or biochemical suspicion of hpHPT, genetic proof or exclusion of hpHPT is necessary. The differentiated treatment approach for hpHTP can only be defined by taking the clinical and diagnostic results of all the abovenamed findings into account.
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Affiliation(s)
- Martina T Mogl
- Chirurgische Klinik, Charité Campus Mitte/Campus Virchow-Klinikum, Berlin, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin und Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Deutschland.
| | - Peter E Goretzki
- Chirurgische Klinik, Charité Campus Mitte/Campus Virchow-Klinikum, Berlin, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin und Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Deutschland
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2
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Wejaphikul K, Dejkhamron P, Khorana J, Watcharachan K, Intachai W, Olsen B, Tongsima S, Ketudat Cairns JR, Ngamphiw C, Kantaputra P. Subtotal Parathyroidectomy Successfully Controls Calcium Levels of Patients with Neonatal Severe Hyperparathyroidism Carrying a Novel CASR Mutation. Horm Res Paediatr 2023; 96:432-438. [PMID: 36626889 DOI: 10.1159/000528568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 11/28/2022] [Indexed: 01/11/2023] Open
Abstract
INTRODUCTION Inactivating mutations of the calcium-sensing receptor (CASR) gene result in neonatal severe hyperparathyroidism (NSHPT). Total parathyroidectomy is an effective way to control life-threatening hypercalcemia in NSHPT but leads to permanent hypoparathyroidism. An alternative surgical option is subtotal parathyroidectomy. However, few cases were reported in the literature. Here, we report two unrelated NSHPT patients, one with a novel homozygous mutation (c.1817T>C; p.Leu606Pro) in CASRand the other with heterozygous for the same mutation who also carried two rare intronic variants in CASR. The outcomes of subtotal parathyroidectomy in these patients are also described. CASE PRESENTATION Two infants presented with an alteration of consciousness, respiratory distress, and bradycardia. Severe hypercalcemia, hypophosphatemia, and markedly elevated parathyroid hormone levels were identified, suggesting NSHPT. Cinacalcet was unable to control calcium (Ca) levels of both patients. A novel heterozygous and homozygous missense mutation c.1817T>C; p.Leu606Pro was identified in patients 1 and 2, respectively. Based on the model prediction, proline substitution at Leu606 is likely to disrupt conversion between the active and inactive conformations at the extracellular to transmembrane domain interface of CASR. In addition, two extremely rare intronic variants in CASR (chr3:g.122180314A>G and chr3:g.122251601G>A, based on GRCh38) were identified in patient 1 and his mother. These variants might have contributed to the clinical manifestations of patient 1 who was heterozygous for the c.1817T>C; p.Leu606Pro variant. Subtotal parathyroidectomy was performed by removing three and a half parathyroid glands. So far, patient 1 has been in normocalcemia for 5 years. Patient 2 was in normocalcemia for 16 months after surgery and subsequently developed mild hypoparathyroidism which required only low-dose calcitriol treatment. CONCLUSION We report a novel heterozygous and homozygous missense variant (c.1817T>C; p.Leu606Pro) in CASR in two NSHPT patients. The mutation likely disrupts conformational changes of CASR and results in cinacalcet unresponsiveness. Intronic variants in CASR identified in the patient with heterozygous variant might have contributed to the clinical manifestations of the patient. Although total parathyroidectomy is widely accepted as a standard treatment for NSHPT, we demonstrate that subtotal parathyroidectomy is also an effective procedure to normalize Ca levels and allow these patients to be in normocalcemia or mild hypoparathyroidism, which is simply controlled by low-dose calcitriol treatment. Subtotal parathyroidectomy appeared to be an effective treatment for NSHPT regardless of the molecular etiologies.
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Affiliation(s)
- Karn Wejaphikul
- Department of Pediatrics, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand,
| | - Prapai Dejkhamron
- Department of Pediatrics, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Jiraporn Khorana
- Department of Surgery, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
- Center of Clinical Epidemiology and Clinical Statistic, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Kirati Watcharachan
- Department of Surgery, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Worrachet Intachai
- Center of Excellence in Medical Genetics Research, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand
| | - Bjorn Olsen
- Department of Developmental Biology, Harvard School of Dental Medicine, Harvard University, Boston, Massachusetts, USA
| | - Sissades Tongsima
- National Biobank of Thailand, National Science and Technology Development Agency, Thailand Science Park, Khlong nueng, Thailand
| | - James R Ketudat Cairns
- Laboratory of Biochemistry, Chulabhorn Research Institute, Bangkok, Thailand
- School of Chemistry, Institute of Science, and Center for Biomolecular Structure, Function and Application, Suranaree University of Technology, Nakhon Ratchasima, Thailand
| | - Chumpol Ngamphiw
- National Biobank of Thailand, National Science and Technology Development Agency, Thailand Science Park, Khlong nueng, Thailand
| | - Piranit Kantaputra
- Center of Excellence in Medical Genetics Research, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand
- Division of Pediatric Dentistry, Department of Orthodontics and Pediatric Dentistry, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand
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Wade L, Aindow A, Isherwood L, Mughal MZ, Ramakrishnan R. Successful use of cinacalcet monotherapy in the management of siblings with homozygous calcium-sensing receptor mutation. J Pediatr Endocrinol Metab 2022; 35:549-556. [PMID: 35073615 DOI: 10.1515/jpem-2021-0632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 12/29/2021] [Indexed: 11/15/2022]
Abstract
OBJECTIVES Neonatal severe hyperparathyroidism (NSHPT) due to pathogenic mutations in the calcium-sensing receptor (CASR) is a serious medical condition that can lead to symptomatic hypercalcaemia and has detrimental effects on a child's growth and development. What is new: This report adds to evidence that homozygous CASR mutations can be managed with cinacalcet monotherapy as an alternative to parathyroidectomy. And, early use of cinacalcet in NSHPT can result in improvements in symptoms, growth and developmental milestones. CASE PRESENTATION We present two siblings with NSHPT due to homozygous mutation in the CASR gene with moderate hypercalcaemia. Both were treated with cinacalcet monotherapy and showed significant improvement in growth parameters including head circumference, developmental milestones and hypercalcaemic symptoms, once their calcium and parathyroid hormone levels normalised. CONCLUSIONS This report highlights the role of cinacalcet in managing elevated serum calcium levels in a select group of infants with NSHPT due to homozygous CASR mutations, resulting in improvement in hypercalcaemic symptoms, growth and neurodevelopmental outcomes.
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Affiliation(s)
- Laura Wade
- Alder Hey Children's NHS Foundation Trust, Liverpool, UK
| | - Anita Aindow
- Alder Hey Children's NHS Foundation Trust, Liverpool, UK
| | | | - M Zulf Mughal
- Manchester Foundation NHS Trust, Manchester, UK.,Faculty of Biology, Medicine & Health, University of Manchester, Manchester, UK
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Bernardor J, Flammier S, Salles JP, Amouroux C, Castanet M, Lienhardt A, Martinerie L, Damgov I, Linglart A, Bacchetta J. Off-label use of cinacalcet in pediatric primary hyperparathyroidism: A French multicenter experience. Front Pediatr 2022; 10:926986. [PMID: 36090548 PMCID: PMC9449487 DOI: 10.3389/fped.2022.926986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Accepted: 07/11/2022] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Cinacalcet is a calcimimetic approved in adults with primary hyperparathyroidism (PHPT). Few cases reports described its use in pediatric HPT, with challenges related to the risk of hypocalcemia, increased QT interval and drug interactions. In this study, we report the French experience in this setting. METHODS We retrospectively analyzed data from 18 pediatric patients from 7 tertiary centers who received cinacalcet for PHPT. The results are presented as median (interquartile range). RESULTS At a median age of 10.8 (2.0-14.4) years, 18 patients received cinacalcet for primary HPT (N = 13 inactive CASR mutation, N = 1 CDC73 mutation, N = 1 multiple endocrine neoplasia type 1, N=3 unknown etiology). Cinacalcet was introduced at an estimated glomerular filtration rate (eGFR) of 120 (111-130) mL/min/1.73 m2, plasma calcium of 3.04 (2.96-3.14) mmol/L, plasma phosphate of 1.1 (1.0-1.3) mmol/L, age-standardized (z score) phosphate of -3.0 (-3.5;-1.9), total ALP of 212 (164-245) UI/L, 25-OHD of 37 (20-46) ng/L, age-standardized (z score) ALP of -2.4 (-3.7;-1.4), PTH of 75 (59-123) ng/L corresponding to 1.2 (1.0-2.3)-time the upper limit for normal (ULN). The starting daily dose of cinacalcet was 0.7 (0.6-1.0) mg/kg, with a maximum dose of 1.0 (0.9-1.4) mg/kg per day. With a follow-up of 2.2 (1.3-4.3) years on cinacalcet therapy, PTH and calcium significantly decreased to 37 (34-54) ng/L, corresponding to 0.8 (0.5-0.8) ULN (p = 0.01), and 2.66 (2.55-2.90) mmol/L (p = 0.002), respectively. In contrast, eGFR, 25-OHD, ALP and phosphate and urinary calcium levels remained stable. Nephrocalcinosis was not reported but one patient displayed nephrolithiasis. Cinacalcet was progressively withdrawn in three patients; no side effects were reported. CONCLUSIONS Cinacalcet in pediatric HPT can control hypercalcemia and PTH without significant side effects.
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Affiliation(s)
- Julie Bernardor
- Centre de Référence des Maladies Rares du Calcium et du Phosphore, Centre de Référence des Maladies Rénales Rares, Filières de Santé Maladies Rares OSCAR, ORKID et ERKNet, Service de Néphrologie Rhumatologie et Dermatologie Pédiatriques, Hôpital Femme Mère Enfant, Bron, France.,INSERM UMR S1033 Research Unit, Lyon, France.,Service de Néphrologie Pédiatrique, CHU de Nice, Hôpital Archet, Nice, France.,Faculté de Médecine, Université Côte d'Azur, Nice, France
| | - Sacha Flammier
- Centre de Référence des Maladies Rares du Calcium et du Phosphore, Centre de Référence des Maladies Rénales Rares, Filières de Santé Maladies Rares OSCAR, ORKID et ERKNet, Service de Néphrologie Rhumatologie et Dermatologie Pédiatriques, Hôpital Femme Mère Enfant, Bron, France
| | - Jean-Pierre Salles
- Centre de Référence des Maladies Rares du Calcium et du Phosphore, Unité d'Endocrinologie, Génétique et Pathologies Osseuses, Filières Santé Maladies Rares OSCAR et BOND, Hôpital des Enfants, Toulouse, France
| | - Cyril Amouroux
- Service d'Endrocrinologie et Néphrologie Pédiatrique, Filière de Santé Maladies Rares OSCAR, Hôpital Arnaud de Villeneuve - CHU Montpellier, Université de Montpellier, Montpellier, France
| | - Mireille Castanet
- Centre de Référence des Maladies Rares du Calcium et du Phosphore, Département de Pédiatrie, Filière Santé Maladies Rares OSCAR, CHU Rouen, Rouen, France
| | | | - Laetitia Martinerie
- Service d'Endocrinologie Pédiatrique, Centre de Référence des Maladies Endocriniennes Rares de la Croissance et du Développement (CRMERCD), Hôpital Robert Debré, Assistance Publique - Hôpitaux de Paris, Paris, France
| | - Ivan Damgov
- Center for Pediatric and Adolescent Medicine, University of Heidelberg, Heidelberg, Germany.,Institute of Medical Biometry and Informatics, University of Heidelberg, Heidelberg, Germany
| | - Agnès Linglart
- AP-HP, Centre de référence des maladies rares du métabolisme du calcium et du phosphate, Plateforme d'expertise maladies rares Paris Saclay, filière OSCAR, EndoRare and BOND ERN, Hôpital de Bicêtre Paris Saclay, Le Kremlin-Bicêtre, France.,Université Paris-Saclay, AP-HP, Service d'endocrinologie et diabète de l'enfant, Service de médecine des adolescents, Hôpital de Bicêtre Paris Saclay, INSERM U1185, Le Kremlin-Bicêtre, France
| | - Justine Bacchetta
- Centre de Référence des Maladies Rares du Calcium et du Phosphore, Centre de Référence des Maladies Rénales Rares, Filières de Santé Maladies Rares OSCAR, ORKID et ERKNet, Service de Néphrologie Rhumatologie et Dermatologie Pédiatriques, Hôpital Femme Mère Enfant, Bron, France.,INSERM UMR S1033 Research Unit, Lyon, France.,Faculté de Médecine Lyon Est, Université de Lyon, Lyon, France
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Çömlek FÖ, Demir S, Gürkan H, İnan M, Sezer A, Dilek E, Kökenli FT. The efficiency of cinacalcet treatment in delaying parathyroidectomy in a case with neonatal severe hyperparathyroidism caused by homozygous mutation in the CASR gene. Pediatr Endocrinol Diabetes Metab 2022; 28:168-174. [PMID: 35399047 PMCID: PMC10214968 DOI: 10.5114/pedm.2022.115070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 02/19/2022] [Indexed: 06/07/2023]
Abstract
Neonatal severe hyperparathyroidism (NSHPT) causes severe hypercalcaemia, metabolic bone disease, and potential neurodevelopmental deficits, all of which can be life-threatening. The use of calcimimetic agents can prevent or delay technically difficult parathyroidectomy in the newborn period. We present a 6-day-old male infant who presented with poor feeding, weight loss, and severe hypotonia. His total serum calcium and parathyroid hormone levels were very high (23.6 mg/dl and 1120 ng/dl, respectively). Based on these findings, the patient was diagnosed with NSHPT and was started on cinacalcet therapy until the genetic analysis results were available. Genetic analysis revealed a previously reported homozygous mutation in the CASR gene that was unresponsive to cinacalcet therapy in the literature. However, a normocalcaemic state unexpectantly occurred, which could be maintained with low calcium formula and cinacalcet therapy up to 13 months of age in the patient. Nevertheless, hypercalcaemia developed 2 months after he started a normal calcium-containing diet. Therefore, the patient underwent total parathyroidectomy at 17 months of age. We would like to emphasize, in light of this case, that cinacalcet treatment may be considered as first-line therapy for delaying parathyroidectomy in all cases with NSHPT, even in those who have an unresponsive cinacalcet CASR gene mutation.
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Affiliation(s)
- Fatma Özgüç Çömlek
- Department of Pediatric Endocrinology, Faculty of Medicine, Trakya University, Turkey
| | - Selma Demir
- Department of Medical Genetic, Faculty of Medicine, Trakya University, Turkey
| | - Hakan Gürkan
- Department of Medical Genetic, Faculty of Medicine, Trakya University, Turkey
| | - Mustafa İnan
- Department of Pediatric Surgery, Faculty of Medicine, Trakya University, Turkey
| | - Atakan Sezer
- Department of General Surgery, Faculty of Medicine, Trakya University, Turkey
| | - Emine Dilek
- Department of Pediatric Endocrinology, Faculty of Medicine, Trakya University, Turkey
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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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7
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Pediatric hyperparathyroidism: review and imaging update. Pediatr Radiol 2021; 51:1106-1120. [PMID: 33904951 DOI: 10.1007/s00247-021-05050-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 01/26/2021] [Accepted: 03/09/2021] [Indexed: 10/21/2022]
Abstract
Hyperparathyroidism, due to increased secretion of parathyroid hormones, may be primary, secondary or tertiary. Most pediatric patients with sporadic primary hyperparathyroidism will be symptomatic, presenting with either end-organ damage or nonspecific symptoms. In younger patients with primary hyperparathyroidism, there is a higher prevalence of familial hyperparathyroidism including germline inactivating mutations of the calcium-sensing receptor genes that result in either neonatal severe hyperparathyroidism or familial hypocalciuric hypercalcemia. Parathyroid scintigraphy and ultrasound are complementary, first-line imaging modalities for localizing hyperfunctioning parathyroid glands. Second-line imaging modalities are multiphase computed tomography (CT) and magnetic resonance imaging. In pediatrics, multiphase CT protocols should be adjusted to optimize radiation dose. Although, the role of these imaging modalities is better established in preoperative localization of hyperfunctioning parathyroid glands in primary hyperparathyroidism, the same principles apply in secondary and tertiary hyperparathyroidism. In this manuscript, we will review the embryology, anatomy, pathophysiology and preoperative localization of parathyroid glands as well as several subtypes of primary familial hyperparathyroidism. While most of the recent imaging literature centers on adults, we will focus on the issues that are pertinent and applicable to pediatrics.
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Tan RSG, Lee CHL, Dimke H, Todd Alexander R. The role of calcium-sensing receptor signaling in regulating transepithelial calcium transport. Exp Biol Med (Maywood) 2021; 246:2407-2419. [PMID: 33926258 DOI: 10.1177/15353702211010415] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The calcium-sensing receptor (CaSR) plays a critical role in sensing extracellular calcium (Ca2+) and signaling to maintain Ca2+ homeostasis. In the parathyroid, the CaSR regulates secretion of parathyroid hormone, which functions to increase extracellular Ca2+ levels. The CaSR is also located in other organs imperative to Ca2+ homeostasis including the kidney and intestine, where it modulates Ca2+ reabsorption and absorption, respectively. In this review, we describe CaSR expression and its function in transepithelial Ca2+ transport in the kidney and intestine. Activation of the CaSR leads to G protein dependent and independent signaling cascades. The known CaSR signal transduction pathways involved in modulating paracellular and transcellular epithelial Ca2+ transport are discussed. Mutations in the CaSR cause a range of diseases that manifest in altered serum Ca2+ levels. Gain-of-function mutations in the CaSR result in autosomal dominant hypocalcemia type 1, while loss-of-function mutations cause familial hypocalciuric hypercalcemia. Additionally, the putative serine protease, FAM111A, is discussed as a potential regulator of the CaSR because mutations in FAM111A cause Kenny Caffey syndrome type 2, gracile bone dysplasia, and osteocraniostenosis, diseases that are characterized by hypocalcemia, hypoparathyroidism, and bony abnormalities, i.e. share phenotypic features of autosomal dominant hypocalcemia. Recent work has helped to elucidate the effect of CaSR signaling cascades on downstream proteins involved in Ca2+ transport across renal and intestinal epithelia; however, much remains to be discovered.
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Affiliation(s)
- Rebecca Siu Ga Tan
- Department of Physiology, University of Alberta, Edmonton T6G 1C9, Canada.,Membrane Protein Disease Research Group, University of Alberta, Edmonton T6G 1C9, Canada
| | | | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense 5000, Denmark.,Department of Nephrology, Odense University Hospital, Odense 5000, Denmark
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton T6G 1C9, Canada.,Membrane Protein Disease Research Group, University of Alberta, Edmonton T6G 1C9, Canada.,Department of Pediatrics, University of Alberta, Edmonton T6G 1C9, Canada
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A novel case of neonatal severe hyperparathyroidism successfully treated with a type II calcimimetic drug. Bone Rep 2021; 14:100761. [PMID: 33748353 PMCID: PMC7972953 DOI: 10.1016/j.bonr.2021.100761] [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: 12/15/2020] [Revised: 02/21/2021] [Accepted: 03/01/2021] [Indexed: 11/24/2022] Open
Abstract
We report a boy with hypercalcemia due to neonatal severe hyperparathyroidism (NSHPT) caused by a compound heterozygous mutation in the calcium sensing receptor (CaSR) managed successfully on a type II calcimimetic drug. The hypercalcemia was temporarily treated by hyperhydration, bisphosphonate and calcium depleted milk. At 29 days of age cinacalcet was introduced. The starting dose was 0.5 mg/kg/day and was subsequently titrated to the point of efficacy (5.2 mg/kg/day) when a persuasive reduction in parathyroid hormone and calcium concentrations was observed. We propose a trial of type II calcimimetics in newborns with NSHPT irrespective of the genetic mutation and advocate that residual functionality of the CaSR predict the drug efficacy.
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Tőke J, Czirják G, Enyedi P, Tóth M. Rare diseases caused by abnormal calcium sensing and signalling. Endocrine 2021; 71:611-617. [PMID: 33528764 PMCID: PMC8016752 DOI: 10.1007/s12020-021-02620-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Accepted: 01/08/2021] [Indexed: 12/20/2022]
Abstract
The calcium-sensing receptor (CaSR) provides the major mechanism for the detection of extracellular calcium concentration in several cell types, via the induction of G-protein-coupled signalling. Accordingly, CaSR plays a pivotal role in calcium homeostasis, and the CaSR gene defects are related to diseases characterized by serum calcium level changes. Activating mutations of the CaSR gene cause enhanced sensitivity to extracellular calcium concentration resulting in autosomal dominant hypocalcemia or Bartter-syndrome type V. Inactivating CaSR gene mutations lead to resistance to extracellular calcium. In these cases, familial hypocalciuric hypercalcaemia (FHH1) or neonatal severe hyperparathyroidism (NSHPT) can develop. FHH2 and FHH3 are associated with mutations of genes of partner proteins of calcium signal transduction. The common polymorphisms of the CaSR gene have been reported not to affect the calcium homeostasis itself; however, they may be associated with the increased risk of malignancies.
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Affiliation(s)
- Judit Tőke
- Department of Internal Medicine and Oncology, Semmelweis University, Budapest, Hungary
| | - Gábor Czirják
- Department of Physiology, Semmelweis University, Budapest, Hungary
| | - Péter Enyedi
- Department of Physiology, Semmelweis University, Budapest, Hungary
| | - Miklós Tóth
- Department of Internal Medicine and Oncology, Semmelweis University, Budapest, Hungary.
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Severe primary hyperparathyroidism in a 3-day-old neonate. JOURNAL OF PEDIATRIC SURGERY CASE REPORTS 2021. [DOI: 10.1016/j.epsc.2020.101719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Makita N, Ando T, Sato J, Manaka K, Mitani K, Kikuchi Y, Niwa T, Ootaki M, Takeba Y, Matsumoto N, Kawakami A, Ogawa T, Nangaku M, Iiri T. Cinacalcet corrects biased allosteric modulation of CaSR by AHH autoantibody. JCI Insight 2019; 4:126449. [PMID: 30996138 DOI: 10.1172/jci.insight.126449] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 03/12/2019] [Indexed: 12/13/2022] Open
Abstract
Biased agonism is a paradigm that may explain the selective activation of a signaling pathway via a GPCR that activates multiple signals. The autoantibody-induced inactivation of the calcium-sensing receptor (CaSR) causes acquired hypocalciuric hypercalcemia (AHH). Here, we describe an instructive case of AHH in which severe hypercalcemia was accompanied by an increased CaSR antibody titer. These autoantibodies operated as biased allosteric modulators of CaSR by targeting its Venus flytrap domain near the Ca2+-binding site. A positive allosteric modulator of CaSR, cinacalcet, which targets its transmembrane domain, overcame this autoantibody effect and successfully corrected the hypercalcemia in this patient. Hence, this is the first study to our knowledge that identifies the interaction site of a disease-causing GPCR autoantibody working as its biased allosteric modulator and demonstrates that cinacalcet can correct the AHH autoantibody effects both in vitro and in our AHH patient. Our observations provide potentially new insights into how biased agonism works and how to design a biased allosteric modulator of a GPCR. Our observations also indicate that the diagnosis of AHH is important because the severity of hypercalcemia may become fatal if the autoantibody titer increases. Calcimimetics may serve as good treatment options for some patients with severe AHH.
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Affiliation(s)
- Noriko Makita
- Department of Endocrinology and Nephrology, The University of Tokyo School of Medicine, Tokyo, Japan
| | - Takao Ando
- Division of Endocrinology and Metabolism, Nagasaki Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Junichiro Sato
- Department of Endocrinology and Nephrology, The University of Tokyo School of Medicine, Tokyo, Japan
| | - Katsunori Manaka
- Department of Endocrinology and Nephrology, The University of Tokyo School of Medicine, Tokyo, Japan
| | - Koji Mitani
- Department of Endocrinology and Nephrology, The University of Tokyo School of Medicine, Tokyo, Japan
| | - Yasuko Kikuchi
- Department of Breast and Endocrine Surgery, The University of Tokyo School of Medicine, Tokyo, Japan
| | - Takayoshi Niwa
- Department of Breast and Endocrine Surgery, The University of Tokyo School of Medicine, Tokyo, Japan
| | - Masanori Ootaki
- Department of Pharmacology, St. Marianna University School of Medicine, Kawasaki, Japan
| | - Yuko Takeba
- Department of Pharmacology, St. Marianna University School of Medicine, Kawasaki, Japan
| | - Naoki Matsumoto
- Department of Pharmacology, St. Marianna University School of Medicine, Kawasaki, Japan
| | - Atsushi Kawakami
- Division of Endocrinology and Metabolism, Nagasaki Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Toshihisa Ogawa
- Breast Center, Dokkyo Medical University Koshigaya Hospital, Saitama, Japan
| | - Masaomi Nangaku
- Department of Endocrinology and Nephrology, The University of Tokyo School of Medicine, Tokyo, Japan
| | - Taroh Iiri
- Department of Endocrinology and Nephrology, The University of Tokyo School of Medicine, Tokyo, Japan.,Department of Pharmacology, St. Marianna University School of Medicine, Kawasaki, Japan
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