Dysregulation of vitamin D metabolism is closely associated with the pathogenesis of various diseases, including vitamin D-dependent rickets type 1A (VDDR-1A), chronic kidney disease-mineral and bone disorder (CKD-MBD), tumor-induced osteomalacia (TIO), granulomatous diseases, and CYP24A1 deficiency-related hypercalcemia. This evidence concerns the gene CYP24A1 and vitamin D-dependent rickets, type 1A.