FHH types 1 and 2 (FHH1, OMIM #145980; FHH2, OMIM #145981) are generally associated with mild asymptomatic hypercalcaemia and caused by loss-of-function mutations of the calcium-sensing receptor (CaSR), a G-protein coupled receptor (GPCR), and G-protein subunit α11 (Gα11), respectively, which are pivotal for regulating PTH secretion and renal tubular calcium reabsorption (2). Here, CASR is linked to Hypercalcemia.