Folate status, nutrition and maternal transmission in Irish families with neural tube defects

Background: Maternal relatives in neural tube defect (NTD) families have elevated rates of NTDs and of other birth defects. Folic acid supplementation raises blood folate levels and prevents most new cases of NTDs. There is little information on blood folate levels among distant relatives, and on the potential relationship of serum folate to maternal transmission. Methods: A cross-sectional study assessed serum folate levels among relatives in Irish families with NTDs to evaluate factors associated with blood folate, including matrilineal effects. 324 relatives gave a blood sample for analysis of serum folate and completed two questionnaires concerning lifestyle and dietary folate. Quartiles of the standardized serum folate distribution were evaluating for statistical significance with chi-square tests. Results: Maternal uncles/aunts were more likely to fall into the lowest quartile of serum folate compared to all other relatives (34.1% vs 22.5%, odds ratio=1.68, 95% confidence interval (CI) 0.83, 3.45, p=0.15), after controlling for current alcohol use and intake of fortified foods. Factors that were associated with higher folate levels included intake of enriched/fortified foods (p=0.001) and supplemental folic acid (p<0.0001). Naturallyoccurring food folate was weakly associated with serum folate (p=0.14). Increasing amounts of dietary folate were directly associated with levels of serum folate in this cohort of relatives in Irish NTD families. Conclusions: The weak association of low levels of serum folate with maternal line probably did not explain the excess risk for birth defects seen among maternal relatives in this cohort. 6 January 2011 Page 3 of 20