Understanding How Neural Tube Defects Occur--And Can Be Prevented.

Neural tube defects occur in 1.3 to 2.0 fetuses per 1000 live births, and are second only to cardiac malformations as the most frequent congenital anomaly in the US. The genetic and environmental influences on neural tube defect formation are currently being investigated. It is now thought that neural tube closure occurs in 5 separate sites, with each site possibly controlled by separate genes and subject to different external influences. Evidence suggests that one basic genetic defect involves homocysteine metabolism. Folic acid supplements before conception reduce both occurrence and recurrence risks. Prenatal screening and diagnosis are available, although management options after diagnosis are limited. Dietary alterations and adjustment of medical therapy prior to conception will reduce neural tube defect occurrence.