ADH1A and hyperphosphatemia: Autosomal dominant hypocalcaemia (ADH) refers to hypocalcemia caused by the defects of CASR. Up to now, 2 types of ADH have been identified: autosomal dominant hypocalcemia types 1 and 2 (ADH1 and ADH2) and they are caused by germline gain-of-function mutations of CASR and its signaling partner, the G-protein subunit α 11 respectively with the former more common.[4] Classically, ADH1 is characterized by hypocalcemia with hyperphosphatemia, normal or low circulating PTH concentrations, and a relative or absolute hypercalciuria.