GCM2 and Hypercalcemia: Two index cases (CA0143 and CA0102) had variants of uncertain significance in the GCM2 gene, and gain-of function mutations in the GCM2 gene cause autosomal dominant hyperparathyroidism type 4 (OMIM, #617343), a disorder characterized by hypercalcemia and elevated PTH secretion by parathyroid glands.