Diseases associated with calcium-sensing receptor

The calcium-sensing receptor (CaSR) plays a pivotal role in systemic calcium metabolism by regulating parathyroid hormone secretion and urinary calcium excretion. The diseases caused by an abnormality of the CaSR are genetically determined or are more rarely acquired. The genetic diseases consist of hyper- or hypocalcemia disorders. Hypercalcaemia disorders are related to inactivating mutations of the CASR gene either heterozygous (autosomal dominant familial benign hypercalcaemia, still named hypocalciuric hypercalcaemia syndrome type 1) or homozygous (severe neonatal hyperparathyroidism). The A986S, R990G and Q1011E variants of the CASR gene are associated with higher serum calcium levels than in the general population, hypercalciuria being also associated with the R990G variant. The differential diagnosis consists in the hypocalciuric hypercalcaemia syndrome, types 2 (involving GNA11 gene) and 3 (involving AP2S1 gene); hyperparathyroidism; abnormalities of vitamin D metabolism, involving CYP24A1 and SLC34A1 genes; and reduced GFR. Hypocalcemia disorders, which are more rare, are related to heterozygous activating mutations of the CASR gene (type 1), consisting of autosomal dominant hypocalcemia disorders, sometimes with a presentation of pseudo-Bartter’s syndrome. The differential diagnosis consists of the hypercalciuric hypocalcaemia syndrome type 2, involving GNA11 gene and other hypoparathyroidism aetiologies. The acquired diseases are related to the presence of anti-CaSR antibodies, which can cause hyper- or especially hypocalcemia disorders (for instance in APECED syndromes), determined by their functionality. Finally, the role of CaSR in digestive, respiratory, cardiovascular and neoplastic diseases is gradually coming to light, providing new therapeutic possibilities. Two types of CaSR modulators are known: CaSR agonists (or activators, still named calcimimetics) and calcilytic antagonists (or inhibitors of the CasR). CaSR agonists, such as cinacalcet, are indicated in secondary and primary hyperparathyroidism. Calcilytics have no efficacy in osteoporosis, but could be useful in the treatment of hypercalciuric hypocalcaemia syndromes

Utility of Population-Level DNA Sequence Data in the Diagnosis of Hereditary Endocrine Disease

Context: Genetic testing is increasingly employed for clinical diagnosis, although variant interpretation presents a major challenge due to high background rates of rare coding-region variation, which may contribute to inaccurate estimates of variant pathogenicity and disease penetrance.Objective: To use the Exome Aggregation Consortium (ExAC) dataset to determine the background population frequencies of rare germline coding-region variants in genes associated with hereditary endocrine disease, and to evaluate the clinical utility of this data.Design, Setting, Participants: Cumulative frequencies of rare non-synonymous single nucleotide variants were established for 38 endocrine disease genes in 60,706 unrelated control individuals. The utility of gene-level and variant-level metrics of tolerability was assessed and the pathogenicity and penetrance of germline variants previously associated with endocrine disease evaluated.Results: The frequency of rare coding region variants differed markedly between genes and was correlated with the degree of evolutionary conservation. Genes associated with dominant monogenic endocrine disorders typically harbored fewer rare missense and/or loss-of-function variants than expected. In silico variant prediction tools demonstrated low clinical specificity. The frequency of several endocrine disease-associated variants in the ExAC cohort far exceeded estimates of disease prevalence, indicating either misclassification or overestimation of disease penetrance. Finally, we illustrate how rare variant frequencies may be used to anticipate expected rates of background rare variation when performing disease-targeted genetic testing.Conclusions: Quantifying the frequency and spectrum of rare variation using population-level sequence data facilitates improved estimates of variant pathogenicity and penetrance and should be incorporated into the clinical decision-making algorithm when undertaking genetic testing

Normocalcaemic hypoparathyroidism: prevalence and effect on bone status in older women. The OPUS study.

There are no consistent data on the prevalence and bone status of normocalcaemic hypoparathyroidism (NHYPO) as defined by normal adjusted calcium and low PTH level. Our aim was to determine the prevalence and the metabolic bone profile of NHYPO in older women, assessing its evolution over time. The second objective was to evaluate the prevalence of other calcium metabolic disorders

A Case Report of Familial Benign Hypocalciuric Hypercalcemia: A Mutation in the Calcium-Sensing Receptor Gene

Familial benign hypocalciuric hypercalcemia (FBHH) is an autosomal dominant trait with high penetrance, clinically manifestating a relatively benign, lifelong, persistent hypercalcemia and hypocalciuria without hypercalcemic related complications. The calcium-sensing receptor (CaSR) plays an important role in the regulation of PTH secretion and calcium metabolism. Here we present a family with FBHH of an autosomal dominant inheritance. A heterozygous mutation of E297K (GAG→AAG, exon 4) of CaSR gene was found in 3 family members. To our knowledge, it is the first confirmed case of FBHH with CaSR gene mutation in Korea

Clinical and outcome comparison of genetically positive vs. negative patients in a large cohort of suspected familial hypocalciuric hypercalcemia

Biochemical suspicion of familial hypocalciuric hypercalcemia (FHH) might provide with a negative (FHH-negative) or positive (FHH-positive) genetic result. Understanding the differences between both groups may refine the identification of those with a positive genetic evaluation, aid management decisions and prospective surveillance. We aimed to compare FHH-positive and FHH-negative patients, and to identify predictive variables for FHH-positive cases. Retrospective, national multi-centre study of patients with suspected FHH and genetic testing of the CASR, AP2S1 and GNA11 genes. Clinical, biochemical, radiological and treatment data were collected. We established a prediction model for the identification of FHH-positive cases by logistic regression analysis and area under the ROC curve (AUROC) was estimated. We included 66 index cases, of which 30 (45.5%) had a pathogenic variant. FHH-positive cases were younger (p = 0.029), reported more frequently a positive family history (p < 0.001), presented higher magnesium (p < 0.001) and lower parathormone levels (p < 0.001) and were less often treated for hypercalcemia (p = 0.017) in comparison to FHH-negative cases. Magnesium levels showed the highest AUROC (0.825, 95%CI: 0.709-0.941). The multivariate analysis revealed that family history and magnesium levels were independent predictors of a positive genetic result. The predictive model showed an AUROC of 0.909 (95%CI: 0.826-0.991). The combination of magnesium and a positive family history offered a good diagnostic accuracy to predict a positive genetic result. Therefore, the inclusion of magnesium measurement in the routine evaluation of patients with suspected FHH might provide insight into the identification of a positive genetic result of any of the CaSR-related genes

Hipercalcemia hipocalciúrica familiar como diagnóstico diferencial de hiperparatiroidismo primario con imágenes negativas

Introduction. Familial hypocalciuric hypercalcemia is a rare inherited calcium metabolism disorder in which an alteration of the parathyroid hormone secretion set-point causes hypercalcemia with relative hypocalciuria. Some data suggest that its prevalence is around 74.1 per 100,000 inhabitants. Often, patients are asymptomatic. However, they can develop mild symptoms and an overactive parathyroid adenoma, its main differential diagnosis. The objective was to describe a patient’s case and highlight the importance of clinical suspicion and diagnosis to avoid unnecessary surgical neck explorations for parathyroid adenomas. Case report. This is the case of a 40-year-old man with a biochemical profile compatible with primary hyperparathyroidism with anatomical and functional images negative for adenoma and a calcium/creatinine clearance ratio below 0.001, considering familial hypocalciuric hypercalcemia. Genetic studies evidence a mutation in the calcium sensor receptor gene and confirm the diagnosis. Discussion. Familial hypocalciuric hypercalcemia’s main differential diagnosis is an overactive parathyroid adenoma. For both, mild or no symptoms may be present; serum calcium exceeds the upper limit, and parathormone is more than 25pg/ml. The calcium/creatinine clearance ratio should be used to differentiate one from the other and avoid unnecessary surgical neck explorations. Besides the lack of information on this topic, evidence supports the use of calcimimetics to treat symptomatic hypercalcemia. Conclusions. Patients with mild hypercalcemia with parathyroid hormone readings above 25pg/ml and a calcium/creatinine clearance ratio below 0.001, or patients with primary hyperparathyroidism with negative imaging, should not undergo surgical neck explorations. In these cases, familial hypocalciuric hypercalcemia is a reliable diagnosis; Cinacalcet may be administered in cases of symptomatic hypercalcemia.Introducción. La hipercalcemia hipocalciúrica familiar es un trastorno hereditario poco común del metabolismo del calcio en donde una alteración del punto de ajuste de la secreción de hormona paratiroidea ocasiona hipercalcemia con hipocalciuria relativa. Algunos datos sugieren que su prevalencia es de alrededor de 74.1 por 100,000 habitantes. Los pacientes muchas veces son asintomáticos. Sin embargo, pueden desarrollar síntomas leves y un adenoma paratiroideo hiperactivo, que representa su principal diagnóstico diferencial. El objetivo fue describir el caso de un paciente y resaltar la importancia de la sospecha y el diagnóstico clínicos para evitar exploraciones quirúrgicas cervicales innecesarias en búsqueda de adenomas paratiroideos. Reporte de caso. Este es el caso de un hombre de 40 años con un perfil bioquímico compatible con hiperparatiroidismo primario, con imágenes anatómicas y funcionales negativas para adenoma, además de una relación de depuración de calcio/creatinina menor a 0.001, con consideración de hipercalcemia hipocalciúrica familiar. Los estudios genéticos evidencian una mutación en el gen del receptor sensor del calcio y confirman el diagnóstico. Discusión. El principal diagnóstico diferencial de la hipercalcemia hipocalciúrica familiar es un adenoma paratiroideo hiperactivo. En ambos casos, es posible que no haya síntomas o que estos sean leves; el calcio sérico excede al límite superior, y la paratohormona es mayor de 25pg/ml. Se debe usar la relación de depuración de calcio/creatinina para diferenciar entre estas patologías y evitar exploraciones quirúrgicas cervicales innecesarias. Aparte de la falta de información sobre este tema, la evidencia apoya el uso de calciomiméticos para tratar la hipercalcemia sintomática. Conclusiones. Los pacientes con hipercalcemia leve, con valores de hormona paratiroidea mayores de 25pg/ml y con una relación de depuración de calcio/creatinina menor de 0.001, o los pacientes con hiperparatiroidismo primario con imágenes negativas, no deben ser sometidos a exploraciones quirúrgicas cervicales. En estos casos, la hipercalcemia hipocalciúrica familiar representa un diagnóstico confiable; se puede administrar Cinacalcet en casos de hipercalcemia sintomática

Obiteljska hipokalciurična hiperkalcemija i receptor osjetljiv na kalcij

Familial hypocalciuric hypercalcemia (FHH ) is a lifelong, benign autosomal dominant disease characterized by hypercalcemia, normal to increased parathyroid hormone level, and a relatively low renal calcium excretion. Inactivation of the calcium-sensing receptor in heterozygous patients results in FHH , while in homozygous patients as well as in compound heterozygous or dominant negative heterozygous patients, it may result in neonatal severe hyperparathyroidism (NSHPT ). Parathyroid surgery is not indicated in FHH and does not lower plasma calcium unless total parathyroidectomy is performed, in which case hypocalcemia ensues. There is currently no definitive medical treatment available, although pamidronate can be used to stabilize these patients before parathyroidectomy. Some NSHPT patients are asymptomatic subsequently in their lives. In this paper, clinical characteristics of this relatively rare disorder are presented.Obiteljska hipokalciurična hiperkalcemija je relativno čest uzrok asimptomatske hiperkalcemije. Obiteljska hipokalciurična hiperkalcemija je autosomno dominantni poremećaj obilježen umjerenom hiperkalcemijom i relativnom hipokalciurijom. Obiteljska hipokalciurična hiperkalcemija nastaje uslijed inaktivirajuće mutacije gena za CaSR, receptor osjetljiv na kalcij. Najčešće ovaj poremećaj ne zahtijeva kirurško liječenje, kako je to slučaj s drugim oblicima primarnog hiperparatireoidizma. Pokušaji da se hiperkalcemija liječi lijekovima nisu bili uspješni i nisu snizili razinu kalcija u serumu. Studije pokazuju da sinakalcet (MimparaR) može zaustaviti nenormalno prepoznavanje serumskog kalcija od strane paratireoidnih žlijezda, tako da dođe do normalne sekrecije paratireoidnog hormona. U ovom radu opisane su kliničke manifestacije ove relativno rijetke bolesti

Diagnóstico e manejo do hiperparatireoidismo primário: uma posição científica do Departamento de Metabolismo Ósseo, a Sociedade Brasileira de Endocrinologia e Metabolismo

OBJECTIVE: To conduct a literature review on the diagnosis and management of primary hyperparathyroidism including the classical hipercalcemic form as well as the normocalcemic variant. MATERIALS AND METHODS: This scientific statement was generated by a request from the Brazilian Medical Association (AMB) to the Brazilian Society for Endocrinology as part of its Clinical Practice Guidelines program. Articles were identified by searching in PubMed and Cochrane databases as well as abstracts presented at the Endocrine Society, Brazilian Society for Endocrinology Annual Meetings and the American Society for Bone and Mineral Research Annual Meeting during the last 5 years. Grading quality of evidence and strength of recommendation were adapted from the first report of the Oxford Centre for Evidence-based Medicine. All grades of recommendation, including D, are based on scientific evidence. The differences between A, B, C and D, are due exclusively to the methods employed in generating evidence. CONCLUSION: We present a scientific statement on primary hyperparathyroidism providing the level of evidence and the degree of recommendation regarding causes, clinical presentation as well as surgical and medical treatment.OBJETIVO: Conduzir uma atualização das últimas evidências científicas a respeito da apresentação, do diagnóstico e do manejo clínico e cirúrgico do hiperparatireoidismo primário clássico e normocalcêmico. MATERIAIS E MÉTODOS: Este documento foi concebido pelo Departamento de Metabolismo Ósseo da Sociedade Brasileira de Endocrinologia e Metabologia (SBEM) a partir daquele oriundo do Programa de Diretrizes da Associação Médica Brasileira (AMB) da SBEM. Realizamos uma revisão dos artigos mais relevantes obtidos nos bancos de dados PubMed e Cochrane, além de abstracts apresentados nos encontros anuais da Endocrine Society, da Sociedade Brasileira de Endocrinologia e da American Society for Bone and Mineral Research dos últimos cinco anos, e classificamos as evidências em níveis de recomendações de acordo com a força científica por tipo de estudo, adaptando o primeiro relato do Oxford Centre for Evidence-based Medicine. Todos os graus de recomendação, incluindo-se o D, foram basea-dos em evidência científica, sendo as diferenças entre o A, B, C e D devidas exclusivamente ao desenho empregado na geração da evidência. CONCLUSÃO: Apresentamos uma atualização científica a respeito do hiperparatireoidismo primário, classificando e graduando em níveis de recomendações as principais evidências científicas sobre as suas causas, as variadas formas de apresentação, seu diagnóstico e tratamento.University of Pernambuco Medical School Ministry of HealthFederal University of São Paulo Medical SchoolFederal University of Parana Medical SchoolUniversity of Brasilia Medical SchoolCatholic University of BrasiliaColumbia University College of Physicians & SurgeonsUNIFESP, Medical SchoolSciEL