Loss-of-function mutations in the CYP24A1 gene, which encodes for the 24-hydroxylase enzyme responsible for the catabolism of 25(OH)D3 and 1,25(OH)2D3, have been described as a rare cause of hypercalcemia associated with nephrocalcinosis and nephrolithiasis, since its first description in 2011 in patients with so-called idiopathic infantile hypercalcemia [3,4]. The gene discussed is CYP24A1; the disease is hypercalcemia disease.