Objective: To evaluate the association between the methylenetetrahydrofolate reductase C/T polymorphism and the prevalence and course of asthma.
Method: Genotypes were determined in 433 asthmatic patients and 1 249 healthy subjects by the polymerase chain reaction and restriction fragment length polymorphism method.
Results: The frequencies of the three genotypes were 40.27% for CC, 48.44% for CT, 11.29% for TT and the frequency of allelic T was 35.51% in controls. The frequency of TT genotype in atopic asthmatic patients was significantly higher than that in controls (P = 0.026). The OR for the TT genotype compared with all CC and CT genotypes was 1.61 (95% CI 1.06 approximately 2.47).
Conclusion: These results imply that homozygosity for this common mutation significantly increases the risk of atopic asthma.