GCM2 and hypoparathyroidism: In mice, a loss of GCM2 results in the absence of parathyroid glands development; in humans, germline frameshift, nonsense, and missense mutations leading to GCM2 inactivation can cause a variant of hereditary hypoparathyroidism; in contrast, activating germline GCM2 variants may cause hereditary pHPT, suggesting that GCM2 acts as a parathyroid proto-oncogene [4, 9].