Retinoic Acid Embryopathy and Vitamin A
Retinoic acids are analogues of vitamin A that act as the active form of the vitamin in establishing and maintaining epithelial differentiation and controlling many embryological genetic programs. All-trans-RA and other isomers act as ligands that bind specific nuclear receptors to form ligand-receptor complex that bind to regulatory DNA sequences and control transcription of genes, especially during embryogenesis. Isotretinoin (13-cis-RA) was licensed in the U.S., under the brand name Accutane) beginning in September 1982 for the treatment of severe cystic acne. Subsequently, adverse outcomes of pregnancies were identified of pregnancies during which women took RA. Follow-up studies of pregnancies exposed to 13-cis-RA have shown that it is a human teratogen that poses unusually high risks for major malformations, developmental disabilities, and abnormal growth. No active research projects with this study population are ongoing.
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Lammer EJ, Armstrong D. Malformations of hindbrain structures among humans exposed to isotretinoin (13-cis-retinoic acid) during early embryogenesis. In: Morris-Kay G (ed), Retinoids in Normal Development and Teratogenesis. Oxford: Oxford University Press, 1992; pp 280-295.
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