Excess alcohol consumed during pregnancy starves embryos of retinoic acid, causing deformities such as small head size and missing brain structures.
Abraham Fainsod at the Hebrew University in Jerusalem and his colleagues had previously developed a laboratory frog model of the effects of alcohol. Given alcohol, the frog embryos recapitulate some of the developmental defects of fetal alcohol syndrome.
Fainsod and Hadas Kot-Leibovich now show that alcohol competes with vitamin A, a precursor of retinoic acid, for an enzyme called RALDH2. Increasing RALDH2 levels allows the embryos to tolerate higher doses of alcohol.