Methylenetetrahydrofolate reductase gene polymorphism as a risk factor for diabetic nephropathy in IDDM patients

A missense mutation in the methylenetetrahydrofolate reductase gene (MTHFR), C677T, results in a thermolabile variant with reduced activity. Elevated levels of homocysteine have been recognized as a risk factor for vascular disease. Insulin-dependent diabetes mellitus (IDDM) is characterized by a higher prevalence of vascular complications. We analyzed the frequency of C677T MTHFR in IDDM and control groups. The genotype distribution did not differ between control subjects (n = 297) and IDDM patients (n = 392) (chi(2) = 5.413, df = 2, P > 0.05). The MTHFR T677T genotype was found significantly more frequently in IDDM patients with diabetic nephropathy (0.216) compared with the IDDM patients without nephropathy (0.056); the odds ratio was 2.635 (95% CI 1.768-3.927). Thus, we suggest that the T677T genotype of the MTHFR gene is an independent risk factor for diabetic nephropathy in IDDM.