Polydactyly of a triphalangeal thumb (Q84242): Difference between revisions

Polydactyly of a triphalangeal thumb is a form of preaxial polydactyly of fingers, characterised by the presence of a usually opposable triphalangeal thumb which may or may not be duplicated. Its shape may vary (wedge to rectangular) and it can be deviated in the radio-ulnar plane (clinodactyly). The involved ligaments, muscles, tendons and joints of the duplicated thumb from distal interphalangeal joint to radiocarpal joint can be hypoplastic, malformed, or absent with varying degrees of stiffness or instability. Two forms have been characterised: unilateral and bilateral. The disease is inherited in an autosomal dominant manner.