Vitamin D status and vitamin D receptor gene polymorphisms and susceptibility to type 1 diabetes in Egyptian children

Abstract

Background: Type 1 diabetes mellitus (T1DM) is recognized as a T-cell-mediated autoimmune disease. Vitamin D compounds are known to suppress T-cell activation by binding to vitamin D receptor (VDR); and thus, VDR gene polymorphisms may be related to T-cell-mediated autoimmune diseases. The aim of this study was to investigate the association between vitamin D status and VDR gene polymorphisms and T1DM.

Materials and methods: One hundred and twenty patients with T1DM and one hundred and twenty controls were enrolled in the study. VDR gene BsmI, FokI, ApaI and TaqI polymorphisms were determined using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). Serum 25-hydroxyvitamin D (25(OH)D) was determined using ELISA.

Result: Serum 25(OH)D levels revealed a vitamin D deficiency or insufficiency in 75% of the patients. The mean levels of vitamin D were significantly lower in patients as compared to their controls (P=<0.001). VDR BsmI Bb and bb genotypes and VDR FokI Ff and ff genotypes were associated with increased risk of T1DM (OR=2.3, 95% CI=1.3-4.2, P=0.005; OR=2.2, 95% CI=1.1-4.7, P=0.04; OR=1.8, 95% CI=1.03-3.04, P=0.04; OR=4.03, 95% CI=1.2-13.1, P=0.01 respectively), while the VDR ApaI and TaqI polymorphisms were not.

Conclusion: Our study indicated that vitamin D deficiency and VDR BsmI and FokI polymorphisms were associated with T1DM in Egyptian children.

Keywords: 25(OH)D; 25-hydroxyvitamin D; BMI; Gene polymorphism; PCR-RFLP; SNPs; T1DM; Type 1 diabetes mellitus; VDR; Vitamin D; Vitamin D receptor; body mass index; polymerase chain reaction restriction fragment length polymorphism; single nucleotide polymorphisms; type 1 diabetes mellitus; vitamin D receptor.