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Triphalangeal thumb-polysyndactyly syndrome

Synonym(s) TPT-PS syndrome
Prevalence <1 / 1 000 000
Inheritance Autosomal dominant
Age of onset Infancy
  • Q74.8
  • C1969369
  • C536563
MedDRA -


Disease definition

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.


It has been described in some large pedigrees.

Clinical description

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).

Genetic counseling

This syndrome is transmitted in an autosomal dominant manner with complete penetrance and variable expression.

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