The Epfn KO, MEM1 cKO, and PTH‐CyclinD1 TG mouse models are associated with hypercalcemia, while the CaSR, Cyp27b1, and VDR KO mouse models have a normal serum calcium level despite elevated PTH due to impaired calcium absorption in the kidneys and intestine. The gene discussed is CYP27B1; the disease is hypercalcemia disease.