This was rapidly confirmed for two hypercalcemic disorders in which the CaSR is hypofunctional: the uncommon disorder known as familial hypocalciuric hypercalcemia (FHH); and the extremely rare disorder known as neonatal severe hyperparathyroidism (NSHPT; Pollak et al., 1993, 1994; reviews: Brown et al., 1995; Hendy et al., 2000). Here, CASR is linked to familial hypocalciuric hypercalcemia.