Infant methionine synthase variants and risk for spina bifida

Editor—The mechanisms underlying the reduction in risk for neural tube defect (NTD) affected pregnancies by maternal folic acid supplementation are unknown. Current research efforts are focusing on candidate genes that encode enzymes involved in folate metabolism. Since homocysteine levels have been raised in some women who delivered infants with NTDs,1 2 the enzymes involved in both folate and homocysteine metabolism have received particular attention. Some, but not all, epidemiological data suggest an association between the C677T mutation in methylenetetrahydrofolate reductase (MTHFR) and increased risk for NTDs.3-6 No association between mutations in cystathionine β synthase and NTD risk has been observed.7 The epidemiological data pertaining to genetic variants of methionine synthase are quite limited.8 9 Methionine synthase catalyses the methylation of homocysteine to methionine using 5-methyltetrahydrofolate, the product of the MTHFR reaction, as the carbon donor. Thus, the investigation of genetic variants of methionine synthase is a prudent area of enquiry for exploring …