THE MYSTERY of neural tube defects is unraveling at an increasingly rapid pace.
On the heels of the finding that folic acid supplements could prevent 60% to 72% of these common birth defects in North American and Northern European populations (JAMA. 1993;269:1257-1261) comes new evidence published this month that there is not one but five separate closures, or "zippers," involved in normal neural tube fusion (Am J Med Genet. 1993;47:5).
Until now, a specific cause could be identified in only 10% of cases, and the rest "were all just lumped together in a giant, unknown soup you couldn't do anything about because you didn't know" what environmental or genetic factors might be at fault, says Margot Van Allen, MD, clinical associate professor of medical genetics at the University of British Columbia Faculty of Medicine, Vancouver, and first author on the neural tube closure article.
Rigid scientific confirmation of Van Allen's