Methylenetetrahydrofolate Reductase (MTHFR) (C677T and A1298C) Polymorphisms and Vascular Complications in Patients with Type 2 Diabetes

To assess whether 2 polymorphisms of the methylenetetrahydrofolate reductase (MTHFR) gene, C677T and A1298C, are risk factors for vascular complications in Tunisian patients with type 2 diabetes mellitus.The MTHFR polymorphisms were genotyped, and plasma homocysteine levels were evaluated in 160 Tunisian patients with type 2 diabetes mellitus.Prevalence of the 2 heterozygous polymorphisms of the thermolabile MTHFR gene (CT and AC) was encountered more commonly in patients with diabetes mellitus than in the healthy controls (p<10-3). Subjects with diabetes had significantly higher homocysteine (Hcy) levels than the control subjects; however, there was no statistical difference in plasma Hcy values between carriers of mutant genotypes (CT/TT for C677T and AC/CC for A1298C) and wild types (CC and AA) in patients with diabetes. Retinopathy was found to be a vascular complication in patients with either the 677CT or the 1298(AC+CC) genotype more commonly than in those with the wild-type genotypes (p=0.003; OR=3.2, 95% CI, 1.4 to 7.4; p<10-3; OR=5.9, 95% CI, 2.7 to 13). Only patients who carry the A1298C mutation (AC+CC) are at risk for at least 1 complication (p=0.002). Double heterozygous mutants were at the greatest risk for retinopathy and for suffering at least 1 complication (p<10-3).Studies involving a larger study population and various ethnic groups are required before ruling out the role of MTHFR gene in type 2 diabetes mellitus and in vascular complications.