Polydactyly: a study of a five generation Indian family.

Preaxial polydactyly was observed in up to five generations of an Indian family living in a village in the Rajkot district (Gujarat). Among the 71 affected members, 45 were males and 26 were females. All these affected members showed preaxial polydactyly manifesting as a well formed, articulated extra digit of the hand or foot. Twenty other cases were also identified with polydactyly involving triphalangeal digits replacing the thumbs or duplication of the big toe(s). To the best of our knowledge, the present family is the largest in which several members have preaxial polydactyly of different types. No other abnormalities were apparent. The present study strongly suggests that preaxial polydactyly with a well formed extra digit, triphalangeal thumbs, and duplication of the big toe can be manifestations of the same autosomal dominant gene. It is likely that other factors are modifying the expression of this gene.