Endocrine Abstracts

The calcium-sensing receptor (CaSR) belongs to family C of G-protein coupled receptors (GPCRs) that bind glutamate, GABA, taste molecules and pheromones. Loss-of-function mutations of the CASR gene located on chromosome 3q21–24, cause familial benign hypocalciuric hypercalcaemia type 1 (FBHH1). The genes causing FBHH2 and FBHH3, whose chromosomal locations are on 19p and 19q13.3, respectively, remain unknown. FBHH3, sometimes called the Oklahoma variant (FBHHO...

Kidney stone disease (KSD) is a recurrent condition with limited prophylactic therapies. This study aimed to use Mendelian randomisation (MR) and colocalization analyses to identify novel drug targets for KSD. Utilising UK Biobank genome-wide association study data for MR, we identified forty-nine 1Mbp regions where genetic loci increase risk of KSD via effects on albumin-adjusted serum calcium or phosphate concentrations. Multi-trait statistical colocalization analyses identi...

Diacylglycerol kinase delta (DGKD) has been implicated in calcium homeostasis and nephrolithiasis by genome-wide association studies. We have previously demonstrated that alterations in expression of DGKD cause biased calcium-sensing receptor (CaSR) signalling in vitro. To further elucidate the physiological role of DGKD we examined the biochemical phenotype of a Dgkd-haploinsufficient (+/-) mutant mouse developed by the International Mouse Phenotyping Consor...

Introduction: The pathogenesis of kidney stone disease (KSD) is poorly understood and has been linked to features of metabolic syndrome (MetS). Using conventional and genetic epidemiological analyses we studied associations of MetS phenotypes with risk of KSD.Methods: Multivariate Cox-proportional hazard models were used to assess association of BMI and waist-hip ratio (WHR) with KSD in 492,380 UK Biobank participants. Causal relationships between WHR, B...

Case history: Vitamin D-dependent rickets type 2 (VDDR2) is an autosomal recessive condition caused by resistance to 1,25(OH)2D3, either through vitamin D receptor (VDR) mutations (type A) or abnormal expression of interfering proteins (type B), resulting in hypocalcaemia despite elevated plasma 1,25(OH)2D3 and parathyroid hormone concentrations. We report a proband, born to Caucasian non-consanguineous parents, who presente...

Heterozygous germline gain-of-function mutations of the extracellular calcium-sensing receptor (CaSR), a G-protein coupled receptor (GPCR), result in autosomal dominant hypocalcaemia type 1 (ADH1), which may cause symptomatic hypocalcaemia with low circulating parathyroid hormone (PTH) concentrations and hypercalciuria. Negative allosteric CaSR modulators, known as calcilytics, rectify the gain-of-function caused by CaSR mutations and are a potential targeted therapy for ADH1....

Familial hypocalciuric hypercalcaemia (FHH) comprises three genetic variants: FHH types 1 and 2 are due to mutations of the calcium-sensing receptor (CaSR) and G-protein subunit alpha-11, whereas, FHH type 3 (FHH3) is caused by heterozygous mutations affecting the Arg15 residue (Arg15Cys, Arg15His, Arg15Leu) of the adaptor-related protein complex 2-sigma subunit (AP2S1), which regulates CaSR endocytosis. FHH is usually associated with mild hypercalcaemia, normal parathyroid ho...

Background: Autosomal dominant hypocalcaemia (ADH) is most commonly due to activating mutations in the Calcium Sensing Receptor (ADH Type 1), in which treatment with vitamin D analogues is frequently associated with hypercalciuria. More recently, activating mutations in the alpha-subunit of the G-protein α-11 (Gα11), encoded by GNA11, have been identified in a small number of ADH kindreds (ADH Type 2). The impact of vitamin D analogue treatment in ADH2 patie...

Mutations of the calcium-sensing receptor (CaSR), G-protein alpha-11 subunit (Gα11), and adaptor protein-2 sigma subunit (AP2σ) resulting in a loss-of-function, cause familial hypocalciuric hypercalcemia types 1-3 (FHH1-3), respectively. We investigated a family with FHH (four affected and two unaffected members) for CaSR, Gα11 and AP2σ mutations, and identified a heterozygous Gα11 missense mutation, Phe220Ser, which is predicted to disrupt a cluster o...

Autosomal dominant hypocalcaemia type 1 (ADH1) is a systemic disorder of calcium homeostasis caused by gain-of-function mutations of the calcium-sensing receptor (CaSR). ADH1 may lead to symptomatic hypocalcaemia, inappropriately low parathyroid hormone (PTH) concentrations and hypercalciuria. Active vitamin D metabolites are the mainstay of treatment for symptomatic ADH1 patients, however their use predisposes to nephrocalcinosis, nephrolithiasis and renal impairment. Calcily...