A review of limb defects in a large fetus collection.

Although a considerable number of papers have been published dealing with the frequency and variety of genetic and nongenetic limb defects in newborns and to a lesser extent among embryos, little has been published about the range of limb defects among spontaneously aborted middle and late-term fetuses. This study reports on 133 limb defects from the Central Laboratory for Human Embryology (CLHE), Seattle, Washington. These constitute 34.1% of the total defective specimens in the collection and 5.4% of the total collection population. It is proposed that 30% of the limb defects described indicate a definite recurrence risk, 27% do not indicate recurrence, and the recurrence risk for 43% is unknown. The most interesting findings from this study include the observation that reduction defects affect predominantly the preaxial side of the upper limb and that addition defects (polydactyly) affect predominantly the postaxial side of the lower limb. The observation in relation to reduction defects agrees with U.S. newborn studies. The observation in relation to polydactyly is exactly opposite the studies of Latin American newborns and Japanese embryos.