Polymorphisms in the vitamin D receptor gene and parathyroid hormone gene in the development and progression of diabetes mellitus and its chronic complications, diabetic nephropathy and non-diabetic renal disease

Abstract

Background: We chose to study polymorphisms of vitamin D receptor gene (VDR) and parathyroid hormone genes (PTH), whose protein products significantly affect calciumphosphate metabolism in kidneys and are implicated in the pathogenesis of diabetes, which may also involve kidney damage.

Methods: Distribution of genotypes of four polymorphisms in VDR gene, i.e, TaqI (rs731236), BsmI (rs1544410) ApaI (rs7975232), FokI (rs2228570) and two polymorphisms of PTH gene, i.e., DraII (rs6256), BstBI (rs6264), were studied using PCRRFLP. Examined groups consisted of 147 patients with diabetes (DM), 47 patients with nondiabetic renal disease (NDRD), 132 patients with diabetic nephropathy (DN) and 118 healthy subjects.

Conclusion: Comparison of DN group and healthy subjects identified statistically significant difference for the FokI polymorphism in VDR gene (P<10-4) and also for the BstBI polymorphism in PTH gene (P=0,023). Differences in DraII polymorphism distribution in PTH gene were statistically significant in each group of patients compared to healthy subjects. In DN patients, the BBFFAATt combination of VDR gene was more frequent than in healthy subjects (P=0,046), and the BbFFAaTt variant was more frequent than in DM2 patients (P=0,018). The BBDD haplotype of PTH gene seems to be a predisposing factor for diabetes itself (P=0,019).