The role of folate transport and metabolism in neural tube defect risk.

Neural tube defects (NTDs) are common congenital malformations in humans. While etiologically heterogeneous, for the most part they are multifactorial in their pathogenesis, having both genetic and environmental factors contributing to their development. In recent years, there has been a great deal of epidemiologic evidence demonstrating that women who received multivitamins containing folic acid periconceptionally had significantly reduced occurrence and recurrence risks for producing infants with such malformations. Unfortunately, the mechanism(s) underlying the beneficial effects of folic acid is not well understood. In this article, we review the fundamental embryological processes involved in closing the neural tube, the relevant epidemiologic data on folic acid supplementation and relative NTD risk, as well as several recent studies of candidate genes for NTD sensitivity that are involved in folate transport and metabolism. Copyright 1999 Academic Press.