A study on frog embryos by researchers from Hebrew University in Israel suggests how exposure to ethanol can result in the teratogenic effects of fetal alcohol spectrum disorder (FASD) (Kot-Leibovich H and Fainsod A. Dis Model Mech. 2009;2[5-6]:295-305).
Previously, scientists had discovered that exposing a frog embryo to alcohol during gastrulation reduces retinoic acid (RA) signaling (which is required for normal embryogenesis) and can result in the abnormalities associated with the disorder. Researchers theorized that alcohol exerts this effect on RA through the enzyme retinaldehyde dehydrogenase 2 (RALDH2), which appears in vertebrate embryos at the onset of gastrulation and is involved in metabolizing vitamin A to RA.
Mitka M. Fetal Alcohol Clues. JAMA. 2009;301(21):2202. doi:10.1001/jama.2009.758