Retinoic Acid Embryopathy

Retinoic acid, an analogue of vitamin A, is known to be teratogenic in laboratory animals and has recently been implicated in a few clinical case reports. To study the human teratogenicity of this agent, we investigated 154 human pregnancies with fetal exposure to isotretinoin, a retinoid prescribed for severe recalcitrant cystic acne. The outcomes were 95 elective abortions, 26 infants without major malformations, 12 spontaneous abortions, and 21 malformed infants. A subset of 36 of the 154 pregnancies was observed prospectively. The outcomes in this cohort were 8 spontaneous abortions, 23 normal infants, and 5 malformed infants. Exposure to isotretinoin was associated with an unusually high relative risk for a group of selected major malformations (relative risk = 25.6; 95 per cent confidence interval, 11.4 to 57.5). Among the 21 malformed infants we found a characteristic pattern of malformation involving craniofacial, cardiac, thymic, and central nervous system structures. The malformations included microtia/anotia (15 infants), micrognathia (6), cleft palate (3), conotruncal heart defects and aortic-arch abnormalities (8), thymic defects (7), retinal or optic-nerve abnormalities (4), and central nervous system malformations (18). The pattern of malformation closely resembled that produced in animal studies of retinoid teratogenesis. It is possible that a major mechanism of isotretinoin teratogenesis is a deleterious effect on cephalic neural-crest cell activity that results in the observed craniofacial, cardiac, and thymic malformations. (N Engl J Med 1985;313:837–41.) Retinoic acids are analogues of vitamin A that display some of its biologic activities. Retinoic acids cannot replace the visual or reproductive functions of vitamin A, but they can assume its roles in stimulating bone growth and epithelial differentiation. Because of their effects on epithelial-cell differentiation and their relatively low toxicity as compared with vitamin A, retinoic acids were developed for the treatment of severe cystic acne and other chronic dermatoses. 1 , 2 The first of these retinoic acids, isotretinoin (13- cis -retinoic acid), was licensed in the United States in September 1982 with the brand name Accutane. According to marketing research . . .