Prevention of neural tube defects: vitamins, enzymes and genes.

Neural tube defects can be prevented by folic acid, although the mechanism of this action is unclear. Studies of a series of folate-related enzymes have so far failed to pin-point the nature of the metabolic defect in the neurulation-stage embryo that is corrected by folic acid. Approximately 30% of neural tube defects appear resistant to folic acid and recent work in a mouse genetic model system suggests that administration of myo-inositol may be a complementary therapeutic option. The large number of mouse genes known to cause neural tube defects provide a starting point for identifying the genetic basis of the human defects.