Vitamin D is a fat-soluble vitamin obtained mainly from sun exposure or alternatively from dietary sources and supplements. Vitamin D is a prohormone that requires activation before exhibiting its pharmacological actions. Therefore, it undergoes metabolism in the liver by CYP2R1 and CYP27A1 to yield 25-hydroxyvitamin D (25(OH)D). Further metabolism in the kidney by CYP27B1 yields calcitriol (1, 25(OH)₂D₃), the active form of vitamin D. Calcitriol binds to the vitamin D receptor (VDR), dimerizes with the retinoid receptor, and translocates to the nucleus to bind to the vitamin D response element. This complex can then induce or repress gene transcription depending on the target gene, either co-activators or co-repressors. Therefore, vitamin D-related disorders may be caused by polymorphic variants of genes coding protein molecules involved in vitamin D metabolism and transport. We conducted a review of research trends for vitamin D gene metabolism polymorphisms.