Polydactyly of a biphalangeal thumb is the most common form of preaxial polydactyly of fingers, a limb malformation syndrome, that is characterized by the duplication of one or more skeletal components of a biphalangeal thumb. Hands are preferentially affected (in bilateral), and the right hand is more commonly involved than the left.
Also indexed as
Polydactyly of a biphalangeal thumbPolydactyly of the thumbPolydactyly of the thumb, bilateralPolydactyly of the thumb, unilateralaccessory thumbextra thumbsupernumerary thumb