Methylenetetrahydrofolate reductase polymorphism in patients with bronchial asthma

Objective: Bronchial asthma is a chronic inflammatory condition of the respiratory tract. The C677T mutation in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene is reported to confer susceptibility to cardiovascular diseases and inflammatory conditions. We hypothesized that TT genotype of MTHFR may influence the development of bronchial asthma and thus examined the C677T polymorphism in our Japanese asthmatic patients. Design: Clinical Investigation. Methods: Genotypes for MTHFR were determined in 461 asthmatic patients (male/female ratio: 248/213) by the polymerase chain reaction and restriction fragment length polymorphism method and the results were compared with those obtained from 1430 healthy subjects (male/female ratio: 939/491). Results: For the male population, the frequency of the TT genotype in asthmatic patients was significantly higher than in healthy subjects (16.9% vs. 11.0%, odds ratio = 1.65, 95% confidence interval: 1.12-2.44, P = 0.011). For the female population, the frequency of the TT genotype in atopic asthmatic patients was insignificantly higher than in non-atopic asthmatic patients (17.3% vs. 11.8%). Conclusion: Our findings suggest that the TT genotype of MTHFR is a probable genetic risk factor for the development of bronchial asthma in Japanese males.