Vitamin D level and Fok-I vitamin D receptor gene polymorphism in Egyptian patients with type-1 diabetes.

Many cellular, preclinical and observational studies support a role of vitamin D in pathogenesis of type-1 diabetes mellitus (DM). The vitamin D receptor (VDR) locus has been studied in different populations for association with susceptibility to immune-mediated diseases, but with inconsistent findings in type-1 DM. This study aimed to investigate vitamin D status in patients with type-1 DM. We examined the frequency of VDR Fokl (rs10735810) gene polymorphism, and its association with serum 25-hydroxyvitamin D (25(OH) D) level in Egyptian patients with type-1 DM. 132 children with type-1 DM and 40 age and sex matched healthy control subjects were studied. VDR Fokl polymorphism was assessed using polymerase chain reaction and restriction fragment length polymorphism (RFLP) analysis. Diabetic children demonstrated lower circulating levels of 25(OH) D than the controls (13.4 +/- 7.6 vs 32.1 +/- 3.8ng/ml) (P < 0.01). Patients with deficient 25(OH) D showed lower calcium levels and higher HbA1c% than those with sufficient levels (8.1 +/- 2.1 versus 9.1 +/- 1.6 mg/dl & 9.9 +/- 2.5 versus 8.1 +/- 1.4%, respectively (P < 0.05). There was no significant difference in the genotype distribution or the allele frequencies of VDR Fokl between patients and controls. The odds ratio (OR) was 1.08 (P = 0.76), and the 95% confidence interval (CI) ranged from 0.64-1.85. The diabetic carriers of the ff genotype showed low serum levels of 25(OH) D and calcium when compared with the carriers of the F allele (9.1 +/- 4.4 vs 13.1 +/- 7 and 13.9 +/- 6.09 ng/ml & 8.1 +/- 2.1 vs 9.1 +/- 1.1 and 9.3 +/- 1.2 mg/dl, respectively) (P < 0.05). In conclusion, 84.8% of children with type-1 DM have low circulating levels of 25(OH) D. These patients have poor glycemic control (56.06%) than those with sufficient levels of 25(OH) D. Fokl polymorphism of VDR gene is associated with vitamin D deficiency but has no significant role in susceptibility to type-1 diabetes.