The association between mother and child MTHFR C677T polymorphisms, dietary folate intake and childhood atopy in a population-based, longitudinal birth cohort

Background A recent study suggested a link between folate metabolism and atopy, based on a positive association between a common polymorphism of the methylenetetrahydrofolate reductase (MTHFR) gene and allergic sensitization in Danish adults. Objective We investigated the associations between MTHFR C677T and allergy or atopy in a large, population-based birth cohort of children and their mothers, the Avon Longitudinal Study of Parents and Children (ALSPAC). We also looked for evidence of a pre-natal effect of maternal folate metabolism on subsequent atopic disease in the offspring. Methods Mothers were recruited in pregnancy and the children followed from birth. Atopy in the child was assessed at 7-8 years of age by skin prick tests to common allergens. Asthma was defined as a physician diagnosis and current symptoms at 71/2 years of age. Asthma and allergy status of the mothers were obtained from self-completion questionnaires. Results Data on MTHFR C677T genotype and allergy were available for 5364 children and on allergy and/or asthma for 7356 mothers. In children, the prevalence of atopy was 20.0% and asthma 10.0% whereas in mothers, the prevalence of self-reported allergy was 42.7% and asthma 11.5%. Atopy in the child was associated with male gender (P < 0.001), less tobacco smoke exposure and higher maternal education. MTHFR C677T genotype was not associated with social factors or dietary folate intake. We found no evidence of associations between the MTHFR C677T variant allele and atopy, allergy or asthma in mothers or children. There was no evidence to support an effect of maternal MTHFR C677T genotype on atopy in the offspring. Conclusion The results of this study do not support the hypothesis that impaired folate metabolism is associated with allergy in adults or children in this population.