The C677T methylenetetrahydrofolate reductase gene mutation in hemodialysis patients.

Hyperhomocysteinemia, which results from renal impairment, may promote arteriosclerosis and glomerulosclerosis. The combined effect of renal failure and a common mutation (C677T) in the methylenetetrahydrofolate reductase gene that leads to serum homocysteine elevations in dialysis patients was investigated. Genotypes were determined at this locus in 545 dialysis patients and 676 healthy subjects, and serum concentrations of total homocysteine and folate were measured in a subgroup of 464 patients. Multiple regression analysis showed that the TT genotype and low serum folate concentration were independent positive predictors of the serum total homocysteine concentration. The negative slope of a regression line relating homocysteine and folate concentrations was significantly steeper for patients with the TT genotype than for other genotypes. Patients with the TT genotype were significantly younger at the time of the study (54.8 +/- 12.9 versus 59.6 +/- 12.3 yr; P < 0.0001) and at initiation of dialysis (46.6 +/- 16.2 versus 51.2 +/- 15.9 yr; P < 0.02) than those with other genotypes. In patients who were older at the time of the study or at initiation of dialysis, the prevalence of the TT genotype was lower than in control subjects. In the middle quartiles (37.1 to 63.0 yr) for age at the start of dialysis, the prevalence of the TT genotype was lower in patients with a longer duration of dialysis. In this cross-sectional study, genotype and serum total homocysteine concentration were not independent risk factors for vascular disease in dialysis patients. These results indicate that the methylenetetrahydrofolate reductase mutation is a significant independent predictor for serum total homocysteine concentration.