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AL-Ramdhan A, AL-Ashwal A, Albagshi H, Alhamrani A, Fahmy E, Alhamrani H, Ben Solan I. Case report: familial hypocalciuric hypercalcemia. AME Case Rep 2024; 8:55. [PMID: 38711891 PMCID: PMC11070985 DOI: 10.21037/acr-23-132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 02/08/2024] [Indexed: 05/08/2024]
Abstract
Background Familial hypocalciuric hypercalcemia (FHH) is a hypercalcemic syndrome that is usually characterized by uncomplicated hypercalcemia and normal longevity. The inheritance pattern is autosomal dominant with high penetrance, and it affects both men and women equally. FHH is caused by mutations that disturb the normal functioning of the calcium-sensing receptor (CaSR) gene. This causes a general lack of sensitivity to calcium, eventually leading to hypercalcemia and low calcium levels in the urine. Case Description We report a case of a healthy 24-year-old female with longstanding hypercalcemia and a family history indicating asymptomatic hypercalcemia. The patient was also asymptomatic and had no significant past medical or surgical history. Laboratory investigations and the genetic study revealed findings suggestive of FHH subtype 1. Conclusions The phenotype of FHH is normal, and symptoms of hypercalcemia are usually not present. Patients with FHH and hypoparathyroidism have lower calcium clearance than controls with hypoparathyroidism. This shows that relative hypocalciuria in FHH is not caused by hyperparathyroidism. Since calcium does not appropriately suppress or affect the parathyroid glands in FHH, this means that FHH is a disorder of abnormal transport of extracellular calcium and/or response to it in at least two organs, the parathyroid gland and the kidney. It is quite similar to primary hyperparathyroidism (pHPT) biochemically hence it is important to differentiate this condition from pHPT and hypercalcemia caused by other diseases to avoid any unnecessary surgical or medical intervention.
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Affiliation(s)
- Abdullah AL-Ramdhan
- Department of Family Medicine, Al Ahsa Family Medicine Academy, Hofuf, Saudi Arabia
| | - Abdullah AL-Ashwal
- Diabetes and Endocrinology, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Hanan Albagshi
- Department of Internal Medicine, King Fahad General Hospital, Al Ahasa, Saudi Arabia
| | - Ahmed Alhamrani
- Department of Pediatrics, Maternity and Child Hospital, Alahasa, Saudi Arabia
| | - Eman Fahmy
- Diabetes and Endocrinology, Faculty of Medicine, Helwan University, Helwan, Egypt
| | - Hassan Alhamrani
- Diabetes and Endocrinology, Almana Hospital, Dammam, Saudi Arabia
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Saglia C, Arruga F, Scolari C, Kalantari S, Albanese S, Bracciamà V, Corso Faini A, Brach Del Prever G, Luca M, Romeo C, Mioli F, Migliorero M, Tessaris D, Carli D, Amoroso A, Vaisitti T, De Sanctis L, Deaglio S. Functional evaluation of a novel nonsense variant of the calcium-sensing receptor gene leading to hypocalcemia. Eur J Endocrinol 2024; 190:296-306. [PMID: 38561929 DOI: 10.1093/ejendo/lvae035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 03/06/2024] [Accepted: 03/08/2024] [Indexed: 04/04/2024]
Abstract
OBJECTIVE The calcium-sensing receptor (CASR) gene encodes a G protein-coupled receptor crucial for calcium homeostasis. Gain-of-function CASR variants result in hypocalcemia, while loss-of-function variants lead to hypercalcemia. This study aims to assess the functional consequences of the novel nonsense CASR variant [c.2897_2898insCTGA, p.(Gln967*) (Q967*)] identified in adolescent patient with chronic hypocalcemia, a phenotype expected for a gain-of-function variants. DESIGN AND METHODS To functionally characterize the Q967* mutant receptor, both wild-type (WT) and mutant CASR were transiently transfected into HEK293T cells and calcium-sensing receptor (CaSR) protein expression and functions were comparatively evaluated using multiple read-outs. RESULTS Western blot analysis revealed that the CaSR mutant protein displayed a lower molecular weight compared with the WT, consistent with the loss of the last 122 amino acids in the intracellular domain. Mitogen-activated protein kinase activation and serum responsive element luciferase assays demonstrated that the mutant receptor had higher baseline activity than the WT. Extracellular-signal-regulated kinase/c-Jun N-terminal kinase phosphorylation, however, remained consistently high in the mutant, without significant modulations following exposure to increasing extracellular calcium (Ca2+o) levels, suggesting that the mutant receptor is more sensitive to Ca2+o compared with the WT. CONCLUSIONS This study provides functional validation of the pathogenicity of a novel nonsense CASR variant, resulting in an abnormally hyperfunctioning protein consistent with the patient's phenotype. Functional analyses indicate that mutant receptor is constitutively active and poorly sensitive to increasing concentrations of extracellular calcium, suggesting that the cytoplasmic tail may contain elements regulating signal transduction.
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Affiliation(s)
- Claudia Saglia
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Francesca Arruga
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Caterina Scolari
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Silvia Kalantari
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Serena Albanese
- Department of Public Health and Pediatric Sciences, University of Torino, Torino 10126, Italy
- Pediatric Endocrinology, Regina Margherita Childrens' Hospital, Torino 10126, Italy
| | - Valeria Bracciamà
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Angelo Corso Faini
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Giulia Brach Del Prever
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Maria Luca
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Carmelo Romeo
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Fiorenza Mioli
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | | | - Daniele Tessaris
- Department of Public Health and Pediatric Sciences, University of Torino, Torino 10126, Italy
- Pediatric Endocrinology, Regina Margherita Childrens' Hospital, Torino 10126, Italy
| | - Diana Carli
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Antonio Amoroso
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Tiziana Vaisitti
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Luisa De Sanctis
- Department of Public Health and Pediatric Sciences, University of Torino, Torino 10126, Italy
- Pediatric Endocrinology, Regina Margherita Childrens' Hospital, Torino 10126, Italy
| | - Silvia Deaglio
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
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Valiente-Gabioud AA, Garteizgogeascoa Suñer I, Idziak A, Fabritius A, Basquin J, Angibaud J, Nägerl UV, Singh SP, Griesbeck O. Fluorescent sensors for imaging of interstitial calcium. Nat Commun 2023; 14:6220. [PMID: 37798285 PMCID: PMC10556026 DOI: 10.1038/s41467-023-41928-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 09/22/2023] [Indexed: 10/07/2023] Open
Abstract
Calcium in interstitial fluids is central to systemic physiology and a crucial ion pool for entry into cells through numerous plasma membrane channels. Its study has been limited by the scarcity of methods that allow monitoring in tight inter-cell spaces of living tissues. Here we present high performance ultra-low affinity genetically encoded calcium biosensors named GreenT-ECs. GreenT-ECs combine large fluorescence changes upon calcium binding and binding affinities (Kds) ranging from 0.8 mM to 2.9 mM, making them tuned to calcium concentrations in extracellular organismal fluids. We validated GreenT-ECs in rodent hippocampal neurons and transgenic zebrafish in vivo, where the sensors enabled monitoring homeostatic regulation of tissue interstitial calcium. GreenT-ECs may become useful for recording very large calcium transients and for imaging calcium homeostasis in inter-cell structures in live tissues and organisms.
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Affiliation(s)
- Ariel A Valiente-Gabioud
- Max Planck Institute for Biological Intelligence, Tools for Bio-Imaging, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Inés Garteizgogeascoa Suñer
- Institute de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire (IRIBHM), 808 Route de Lennik, Université Libre de Bruxelles (ULB), 1070, Brussels, Belgium
| | - Agata Idziak
- Institut Interdisciplinaire de Neurosciences, Synaptic Plasticity and Super-Resolution Microscopy, CNRS - Université de Bordeaux - 146 rue Léo-Saignat, Bordeaux, France
| | - Arne Fabritius
- Max Planck Institute for Biological Intelligence, Tools for Bio-Imaging, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Jérome Basquin
- Structural Cell Biology, Max-Planck-Institute for Biochemistry, Am Klopferspitz 18, Martinsried, 82152, Germany
| | - Julie Angibaud
- Institut Interdisciplinaire de Neurosciences, Synaptic Plasticity and Super-Resolution Microscopy, CNRS - Université de Bordeaux - 146 rue Léo-Saignat, Bordeaux, France
| | - U Valentin Nägerl
- Institut Interdisciplinaire de Neurosciences, Synaptic Plasticity and Super-Resolution Microscopy, CNRS - Université de Bordeaux - 146 rue Léo-Saignat, Bordeaux, France
| | - Sumeet Pal Singh
- Institute de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire (IRIBHM), 808 Route de Lennik, Université Libre de Bruxelles (ULB), 1070, Brussels, Belgium
| | - Oliver Griesbeck
- Max Planck Institute for Biological Intelligence, Tools for Bio-Imaging, Am Klopferspitz 18, 82152, Martinsried, Germany.
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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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Werner LE, Wagner U. Calcium-sensing receptor-mediated NLRP3 inflammasome activation in rheumatoid arthritis and autoinflammation. Front Physiol 2023; 13:1078569. [PMID: 36685206 PMCID: PMC9854345 DOI: 10.3389/fphys.2022.1078569] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 11/17/2022] [Indexed: 01/09/2023] Open
Abstract
The calcium-sensing receptor (CaSR) is expressed in many cell types - including immune cells and in particular circulating monocytes. Here, the receptor plays an important physiological role as a regulator of constitutive macropinocytosis. This review article provides an overview of the literature on the role of the calcium sensing receptor in the context of inflammatory processes. Special emphasis is laid upon the importance for monocytes in the context of rheumatoid arthritis. We have shown previously, that stimulation of the receptor by increased extracellular Ca2+ ([Ca2+]ex) triggers a pro-inflammatory response due to NLRP3 inflammasome assembly and interleukin (IL)-1β release. The underlying mechanism includes macropinocytosis of calciprotein particles (CPPs), which are taken up in a [Ca2+]ex-induced, CaSR dependent manner, and leads to strong IL-1β release. In rheumatoid arthritis (RA), this uptake and the resulting IL-1β release is significantly increased due to increased expression of the receptor. Moreover, increased [Ca2+]ex-induced CPP uptake and IL-1β release is associated with more active disease, while CaSR overexpression has been reported to be associated with cardiovascular complications of RA. Most importantly, however, in animal experiments with arthritic mice, increased local calcium concentrations are present, which in combination with release of fetuin-A from eroded bone could contribute to formation of CPPs. We propose, that increased [Ca2+]ex, CPPs and pro-inflammatory cytokines drive a vicious cycle of inflammation and bone destruction which in turn offers new potential therapeutic approaches.
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Ibrahim I, Syamala S, Ayariga JA, Xu J, Robertson BK, Meenakshisundaram S, Ajayi OS. Modulatory Effect of Gut Microbiota on the Gut-Brain, Gut-Bone Axes, and the Impact of Cannabinoids. Metabolites 2022; 12:metabo12121247. [PMID: 36557285 PMCID: PMC9781427 DOI: 10.3390/metabo12121247] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 11/30/2022] [Accepted: 12/08/2022] [Indexed: 12/14/2022] Open
Abstract
The gut microbiome is a collection of microorganisms and parasites in the gastrointestinal tract. Many factors can affect this community's composition, such as age, sex, diet, medications, and environmental triggers. The relationship between the human host and the gut microbiota is crucial for the organism's survival and development, whereas the disruption of this relationship can lead to various inflammatory diseases. Cannabidiol (CBD) and tetrahydrocannabinol (THC) are used to treat muscle spasticity associated with multiple sclerosis. It is now clear that these compounds also benefit patients with neuroinflammation. CBD and THC are used in the treatment of inflammation. The gut is a significant source of nutrients, including vitamins B and K, which are gut microbiota products. While these vitamins play a crucial role in brain and bone development and function, the influence of gut microbiota on the gut-brain and gut-bone axes extends further and continues to receive increasing scientific scrutiny. The gut microbiota has been demonstrated to be vital for optimal brain functions and stress suppression. Additionally, several studies have revealed the role of gut microbiota in developing and maintaining skeletal integrity and bone mineral density. It can also influence the development and maintenance of bone matrix. The presence of the gut microbiota can influence the actions of specific T regulatory cells, which can lead to the development of bone formation and proliferation. In addition, its metabolites can prevent bone loss. The gut microbiota can help maintain the bone's equilibrium and prevent the development of metabolic diseases, such as osteoporosis. In this review, the dual functions gut microbiota plays in regulating the gut-bone axis and gut-brain axis and the impact of CBD on these roles are discussed.
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Affiliation(s)
- Iddrisu Ibrahim
- The Microbiology Program, Department of Biological Sciences, College of Science, Technology, Engineering, and Mathematics (C-STEM), Alabama State University, Montgomery, AL 36104, USA
| | - Soumyakrishnan Syamala
- Departments of Medicine, SUNY Downstate Health Sciences University, Brooklyn, NY 11203, USA
| | - Joseph Atia Ayariga
- The Industrial Hemp Program, College of Science, Technology, Engineering, and Mathematics (C-STEM), Alabama State University, Montgomery, AL 36104, USA
- Correspondence: (J.A.A.); (O.S.A.)
| | - Junhuan Xu
- The Industrial Hemp Program, College of Science, Technology, Engineering, and Mathematics (C-STEM), Alabama State University, Montgomery, AL 36104, USA
| | - Boakai K. Robertson
- The Microbiology Program, Department of Biological Sciences, College of Science, Technology, Engineering, and Mathematics (C-STEM), Alabama State University, Montgomery, AL 36104, USA
| | - Sreepriya Meenakshisundaram
- Department of Microbiology and Biotechnology, JB Campus, Bangalore University, Bangalore 560 056, Karnataka, India
| | - Olufemi S. Ajayi
- The Industrial Hemp Program, College of Science, Technology, Engineering, and Mathematics (C-STEM), Alabama State University, Montgomery, AL 36104, USA
- Correspondence: (J.A.A.); (O.S.A.)
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Sviridonova MA. [Syndrome of hypocalсiuric hypercalcemia. Is it rare? Two clinical cases in an outpatient clinic]. PROBLEMY ENDOKRINOLOGII 2022; 68:24-31. [PMID: 36337015 DOI: 10.14341/probl13125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 06/17/2022] [Accepted: 06/17/2022] [Indexed: 11/09/2022]
Abstract
Hypocalciuric hypercalcemia syndrome (familial hypocalciuric hypercalcemia, FHH) is an inherited condition based on dysfunction of the calcium receptor or its associated partner proteins. Recent evidence suggests that the prevalence of this condition may be comparable to that of primary hyperparathyroidism. Clinical manifestations of FHH are usually absent; however the classic symptoms of hypercalcemia may be present in some cases. Timely differential diagnosis of FHH avoids unnecessary and expensive instrumental examination, as well as ineffective treatment. The clinical cases presented in this publication demonstrate the unjustified difficulties in this issue and the necessity to raise the awareness of physicians about the familial hypocalciuric hypercalcemia.
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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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