Genetic testing revealed a novel heterozygous CASR p.Tyr161* mutation and a homozygous SLC12A3 p.Thr60Met mutation, which ultimately confirmed the diagnosis of familial hypocalciuric hypercalcemia type 1 (FHH1) combined with GS. The gene discussed is SLC12A3; the disease is Familial hypocalciuric hypercalcemia type 1.