The VDR gene FokI polymorphism is associated with gestational diabetes mellitus in Turkish women

BACKGROUND: The association between the vitamin D receptor (VDR) gene and gestational diabetes mellitus (GDM) has not been investigated in Turkish pregnant women. We aimed to investigate associations between VDR gene BsmI (rs15444410), ApaI (rs7975232), FokI (rs19735810), and TaqI (rs731236) single nucleotide polymorphisms (SNPs) and GDM. MATERIAL-METHODS: This case-control study comprised 100 women with GDM and 135 pregnant women without GDM. The VDR polymorphism was evaluated using Sanger-based DNA sequencing. RESULT: VDR gene ApaI, BsmI, and TaqI SNPs did not differ between women with and without GDM (each, p > 0.05). ApaI, BsmI, and TaqI were not associated with GDM risk. The VDR gene FokI CT/TT genotype was associated with an increased GDM risk (CT vs. CC, OR = 1.84, 95% CI: [1.05–3.23], p = 0.031; TT vs. CC, OR = 3.95, 95% CI: [1.56–9.96], p = 0.002; CT/TT vs. CC, OR = 2.29, 95% CI: [1.35–3.89], p = 0.002; and CT/CC vs. TT, OR = 3.02, 95% CI: [1.23–7.38], p = 0.012). The FokI-TT genotype was more associated with younger age and higher glucose, HbA1c, and HOMA-IR than the CC and CT genotype. FokI-T was positively correlated with log-HOMA-IR (r = 0.326, p = 0.004). FokI SNPs were independently associated with GDM after adjusting for BMI and age (β = 1.63, 95% CI: [1. 2-4.2], p = 0.012). There were no associations between the FokI, ApaI, BsmI and TaqI haplotypes and GDM. CONCLUSION: VDR gene FokI SNPs were independently associated with having GDM in Turkish women. VDR gene FokI SNPs might contribute to insulin resistance of developing GDM.