Association between vitamin D receptor (FokI) genetic variant rs2228570 and iron profile in hemodialysis patients

Iron deficiency is a common etiology of anemia that causes suboptimal response to erythropoietin therapy in hemodialysis (HD) patients. This study investigated the association between vitamin D receptor (VDR) genetic variant (FokI) rs2228570 with iron indices (serum iron, transferrin, transferrin saturation, and ferritin). Sixty adequately hemodialyzed patients subdivided into two groups; 31 patients with transferrin saturation (TSAT) < 20% and 29 with TSAT > 20% who received I.V sodium ferric gluconate, calcium, and vitamin D. Sixty normal healthy were selected as the control group.. VDR genetic variant (SNP rs2228570) was genotyped in all subjects using PCR/RFLP. HD patients showed a higher frequency of rs2228570 FF genotype (38.3%) than controls (31.7%). The frequency of ff genotype and f allele in patients (8.4 and 35% respectively) were significantly lower than controls (25 and 46.7% respectively). Allele model (f vs. F): OR 0.721, 95% CI 0.521-0.998, P = 0.049. While (ff vs. FF): OR 0.452, 95% CI 0.223-0.917, P = 0.028. The distribution of Ff + ff genotypes in HD cases with TSAT > 20% was higher than in HD cases with TSAT < 20%, Dominant model (Ff +ff vs FF): OR 2.753, 95% CI 1.902-3.409, P = 0.048. f allele showed lower frequency in low TSAT group than high TSAT group (27.4 vs. 43.1%) with significant P value (P = 0.042) with allele model (f vs. F): OR 2.012, 95% CI 1.923-4.226, P = 0.042. Fok-1 ff, Ff + ff genotypes were significantly associated with TSAT > 20% with a protective effect against low TSAT in HD patients.