Our patient had an elevated 1,25 dihydroxyvitamin D with normal 25 hydroxyvitamin D and low PTH, which means that the hypercalcemia was caused by the increased production of 1,25 dihydroxyvitamin D through the humoral hypercalcemia of malignancy pathway [6, 7]. The gene discussed is PTH; the disease is hypercalcemia disease.