A rare association of triphalangeal thumbs and duplication of the big toes is described. The family pedigree confirms autosomal dominant inheritance with marked penetrance. A systematic approach to the diagnosis of this anomaly is presented. The distinction between the two types of triphalangeal thumb, true (opposable) and finger-like (non-opposable), is emphasised.

Angular deformity of the thumb is most often caused by a delta phalanx or a longitudinally bracheted diaphysis in a triphalangeal thumb. In some angled thumb, however, triangular-shaped secondary ossification center can cause the deformity, which can be called “abnormal triangular epiphysis” of the thumb. A few clinicians have reported this entity, but they do that utilise this term instead cla...

Triphalangeal thumb (TPT), a long, finger-like thumb with three phalanges instead of two, is regarded as a subtype of preaxial polydactyly. It can occur as a sporadic disorder, but is more often seen as a dominant familial trait. We describe four white Dutch families in which triphalangeal thumb has variable expression and is sometimes associated with preaxial extra rays, rudimentary postaxial ...

Triphalangeal thumb is characterized by the interposition of an extra-phalanx between two normal ones. In this article the authors present the case of a 24-year-old man with bilateral triphalangeal thumb of opposable type, without any other associated anomaly or genetic syndrome. The patient had triangular delta extra-phalanxes that caused ulnar deviation of both thumbs. Surgical procedure for ...

A locus for triphalangeal thumb, variably associated with pre-axial polydactyly, was previously identified in the zone of polarizing activity regulatory sequence (ZRS), a long range limb-specific enhancer of the Sonic Hedgehog (SHH) gene at human chromosome 7q36.3. Here, we demonstrate that a 295T>C variant in the human ZRS, previously thought to represent a neutral polymorphism, acts as a domi...

Triphalangeal thumb (TPT), a rare malformation of uncertain pathogenesis, may occur as an isolated defect, in association with other malformations of the hands, or as a feature of a syndrome or sequence. Isolated TPT occurs in two functional types: opposable and non-opposable. The latter appears to be inherited as a simple autosomal dominant trait, while the former is generally sporadic. TPT is...

BACKGROUND Having reviewed the studies on the biphalangeal fifth toe, we have observed a great disparity of data depending on the research center. We have investigated the frequency of biphalangeal toes and also its handedness. We have also analyzed the relationship of pathological deviations of fifth toe with this feature and with the fifth metatarsal. METHODS We performed a descriptive pros...

This report describes a family with bilateral non-opposable triphalangeal thumb, bringing to two the number of families with this autosomal dominant disorder.