Maternal MTHFR genotype and haplotype predict deficits in early cognitive development in a lead-exposed birth cohort in Mexico City

Background: Maternal folate nutritional status and prenatal lead exposure can influence fetal development and subsequent health. The methylenetetrahydrofolate reductase (MTHFR) gene is important for folate metabolism, and 2 common polymorphisms, C677T and A1298C, reduce enzymatic activity; C677T is present at high penetrance in Mexican populations. Objective: The objective of this study was to examine potential links between maternal and child MTHFR polymorphisms and child neurodevelopment in a lead-exposed population. Design: Data regarding MTHFR polymorphisms C677T and A1298C, peri- and postnatal lead measures, and Bayley Mental Development Index at 24 mo of age (MDI-24) scores were available for 255 mother-child pairs who participated in the ELEMENT (Early Life Exposures in Mexico to Environmental Toxicants) study during 1994-1995. Results: In covariate-adjusted regression models, maternal MTHFR 677 genotype predicted MDI-24 scores, in which each copy of the maternal MTHFR 677T variant allele was associated with lower MDI-24 scores (β = -3.52; 95% CI: -6.12, -0.93; P = 0.004). Maternal MTHFR haplotype also predicted MDI-24 scores (mean ± SE: 93.3 ± 1.2 for 677C-1298A compared with 89.9 ± 0.8 for 677T-1298A; P< 0.05). MDI-24 scores were not associated with maternal MTHFR 1298 genotype or child MTHFR genotypes. We did not observe significant MTHFR genotype x lead interactions with respect to any of the subject biomarkers of lead exposure. Conclusions: The maternal MTHFR 677T allele is an independent predictor of poorer child neurodevelopment at 24 mo. These results suggest that maternal genetic variations in folate metabolism during pregnancy may program offspring neurodevelopment trajectories. Further research is warranted to determine the generalizability of these results across other populations.