Triphalangeal thumb-polysyndactyly syndrome (TPT-PS) is a hand-foot malformation characterized by triphalangeal thumbs and pre- and postaxial polydactyly, isolated syndactyly or complex polysyndactyly.Last update: November 2010
It has been described in some large pedigrees.
Clinical presentation is variable within families, ranging from mild to severe. Malformations of the feet are usually less severe than those of the hands.
TPT-PS is caused by duplication encompassing the limb-specific regulatory element (ZRS) of sonic hedgehog SHH, which lies in intron 5 of the `limb region 1 homolog' gene, LMBR1 (7q36).
This syndrome is transmitted in an autosomal dominant manner with complete penetrance and variable expression.