Any familial hypocalciuric hypercalcemia in which the cause of the disease is a mutation in the AP2S1 gene. The disease is familial hypocalciuric hypercalcemia 3 (Monarch Disease Ontology term MONDO_0010926). Also known as: AP2S1 familial hypocalciuric hypercalcemia, FHH type 3, HHC3, familial hypocalciuric hypercalcemia caused by mutation in AP2S1, familial hypocalciuric hypercalcemia type 3, hpocalciuric hypercalcemia, type III, hypocalciuric hypercalcemia type III.