We showed that hypercalcemia could be successfully controlled with cinacalcet in one patient (Case 1) with the GCM2 p.Tyr394Ser rs142287570 variant, and that resection of more than one gland may be necessary to cure the disease as multiple parathyroid glands can be involved, otherwise leading to failed surgery. This evidence concerns the gene GCM2 and Hypercalcemia.