Impact of vitamin D receptor gene polymorphisms in pathogenesis of Type-1 diabetes mellitus

• Published in: International journal of clinical and experimental medicine Vol. 7; no. 12; pp. 5505 - 5510
• Main Authors: Kamel, Mahmoud M, Fouad, Shawky A, Salaheldin, Omina, El-Razek, Abd El-Rahman A Abd, El-Fatah, Abeer I Abd
• Format: Journal Article
• Language: English
• Published: United States e-Century Publishing Corporation 01.01.2014
• Subjects: Original; Vitamin D receptor (VDR); type 1 diabetes mellitus (TIDM); polymorphism
• ISSN: 1940-5901; 1940-5901

Type 1 diabetes mellitus (TIDM) results from an immune-mediated destruction of insulin-producing-cells in the pancreatic islets of Langerhans. There are clear differences in immunogenetic predisposition to type1 diabetes among countries. Studies have indicated that vitamin D supplementation in early childhood decreases the risk of TIDM. Vitamin D exerts its action via the nuclear vitamin D receptor (VDR), which shows an extensive polymorphism. VDR gene polymorphisms have been associated with altered gene expression or gene function. Four single nucleotide polymorphisms (SNPs) in the VDR gene produce variation in four recognition sites. These recognition sites variants include Fok I, Bsm I, Apa I and Taq I. TO investigate the relationship between VDR gene polymorphisms (at positions Taq I and Apa I) and the incidence of TIDM in Egyptian peoples. This study included 74 patients with type 1 DM in addition to 28 healthy age and sex matched control subjects. All of them were subjected to full history taking and clinical examination. Three ml of venous blood were withdrawn from each patient at fasting and postprandial times and used for genomic DNA extraction, estimation of Hb A1C, as well as, fasting and postprandial C-peptide and blood glucose levels. Apa I recognition site was found in low frequency in diabetic patients (14/74) 18.9% while, its frequency was high (16/28) 57.1% among normal subjects. Taq I has two recognition sites. The first was found at nucleotide number 293 that was found in a frequency of (2/28) 7.1% in normal non-diabetic individuals while it was detected in (14/74) 18.9% in diabetic patients. The second Taq I recognition site was found at nucleotide number 494 without any differences between diabetic and normal individuals. This study indicates that there is an association between VDR genetic polymorphism and incidence of TIDM in Egyptian patients.