VDR and osteoporosis: Some single-nucleotide polymorphisms (SNPs) in VDR fundamentally influence its function, thus leading to osteoporosis.8 The presence of the T allele in rs11568820 leads to greater calcium absorption and increases bone mass.9 T/C alleles in rs4516035 encode VDRA and VDRB1, respectively, with different transcriptional activities.8 In FokI (rs2228570), the T allele increases the risk of osteoporosis.