Polydactyly, postaxial, type B.

Postaxial polydactyly, type B is almost always an isolated, mild malformation with no medical significance. Postaxial polydactyly, types B and A occurred in several infants, suggesting that either the underlying mutation(s) can cause both types of postaxial polydactyly or that some affected infants have more than one mutation. Autosomal dominant inheritance with variable expressivity is postulated.