CYP2R1 and systemic lupus erythematosus: SNPs reported in key enzymes and proteins involved in vitamin D metabolism such as rs2282679 in GC, rs10741657 in CYP2R1, rs10877012 in CYP27B1 and FokI (rs2228570), BsmI (rs1544410), ApaI (rs7975232), and TaqI (rs731236) in VDR, and the haplotypes aBF and ABF(or also interpreted as FBa and FBA according to their location in VDR gene), which means that this combination of alleles (a/A of ApaI, B of BsmI, F of FokI) are associated with genetic risk to SLE and higher clinical disease activity score, respectively [31].