Teratogen update: clinical aspects of thalidomide embryopathy--a continuing preoccupation.

There is much misinformation in the medical community regarding the thalidomide syndrome. Some physicians and scientists are unaware of the fact that organs other than the limbs were frequently affected. Some believe that thalidomide could produce any type of limb reduction defect. Most were aware of the very narrow period of early organogenesis during which the thalidomide-type malformations could be produced. Important features include the fact that limb reduction defects were primarily preaxial, included concomitant girdle hypoplasia when limb reductions were severe, were almost universally bilateral and did not include distal transverse-type defects often called "hemimelia". While it can be said that some spontaneous (non-thalidomide) malformations can mimic the thalidomide syndrome, it can also be said that many limb reduction defects can be determined not to have been produced by thalidomide. The risks of the various defects can be estimated following exposure, with most certainty for limb defects, with less certainty for other defects. Many defects were not associated with exposure to thalidomide such as cleft lip and severe mental retardation.