Then some gene expressions are regulated after 1,25-dihydroxyvitamin D combining with VDR.[11] Previous studies also found that low levels of vitamin D could be a risk of BPH.[8] The VDR gene is a member of the steroid hormone receptor superfamily and is found on chromosome 12, which has the 4 most common polymorphic loci: Fok-1, Bsm-1, Taq-1, and Apa-1.[12] It activates the vitamin D and forms a heterodimer complex that binds to the vitamin D response element. This evidence concerns the gene VDR and benign prostatic hyperplasia.