Autosomal dominant hypocalcemia type 1 (ADH1) and ADH2 (Online Mendelian Inheritance in Man [OMIM] numbers 601198 and 615361) are caused by germline gain-of-function mutations of the calcium-sensing receptor (CaSR) and G protein subunit α-11 (1, –, 4), respectively, which play a pivotal role in the parathyroid and renal regulation of extracellular calcium (Ca2+o) concentrations. This evidence concerns the gene ADH1A and autosomal dominant hypocalcemia 1.