Hereditary index finger polydactyly: phenotypic, radiological, dermatoglyphic, and genetic findings in a large family.

Index finger polydactyly in a Turkish family is reported. The transmission of the malformation fits the pattern of regular autosomal dominant inheritance. Some of the affected individuals had one or two phalanges on their first digits, but all had triphalangeal second fingers. Subjects with polydactyly had very interesting dermatoglyphs, such as an extra a triradius under the super-numerary index finger, the proximal radiant of this triradius (an extra A-line) ending on the radial border of the hand, and arch tibials in the hallucal areas. The carpal bones, beginning with os multangulum majus, or alternatively with the extra one were articulated with two metacarpals. A similar finding was found in the feet.