Role of vitamin D receptor genetic variants (ApaI and FokI) in association with nephropathy stages in a group of Egyptian patients with type 2 diabetes mellitus

Diabetic nephropathy (DN) is one of the most worrisome complications of diabetes, causing significant social and economic impacts. Genetic polymorphisms in vitamin D receptor (VDR) gene may lead to genomic instability and increase susceptibility to end-stage renal disease (ESRD). In this research, we aimed to identify the association of genetic variants: ApaI "rs7975232" and FokI "rs10735810" in the VDR gene with nephropathy stages in diabetic patients. This case-control hospital-based study included 200 Egyptian participants divided into a group of 150 patients with type 2 diabetes mellitus (T2DM), divided into three subgroups according to albumin/creatinine ratio, and 50 age and sex matched participants as a normal control group. Genetic variants in the VDR gene were detected using restriction fragment length polymerase chain reaction to evaluate their association with kidney disease stage and bone density in T2DM patients. Our results revealed that aa genotype and a allele frequency in ApaI "rs7975232" and ff genotype and f allele frequency in FokI "rs10735810" were more frequent in diabetic patients than in the normal control group (p < 0.001). In addition, our results revealed that T2DM patients with the ApaI aa genotype and a allele were at a higher risk of developing ESRD as they were almost 13-fold higher than those with the (Aa/AA) genotype and A allele. Also, we found that carriers of the ff genotype and f allele of FokI are at 17-fold and 7-fold higher risk of ESRD than carriers of the non-ff genotype. In conclusion, our study findings indicated that the FokI f allele and the ApaI a allele variant of VDR gene could be used as molecular biomarkers to predict the risk of diabetes and nephropathy stages in Egyptian patients.