Triphalangeal thumb (TPT) is a rare human hand-foot malformation characterized by a long, finger-like thumb with three phalanges. It can occur either in isolated form or in association with other defects such as triphalangeal thumb-polydactyly syndrome (TPT-PS). TPT is caused by defects in a cis-regulatory sequence ZRS, located in intron 5 of LMBR1, which is crucial for expression of sonic hedgehog (SHH) during limb development.
Category
Congenital malformation
Brite
Human diseases in ICD-11 classification [BR:br08403]
20 Developmental anomalies
Multiple developmental anomalies or syndromes
LD26 Syndromes with limb anomalies as a major feature
H00855 Triphalangeal thumb-polysyndactyly syndrome
Farooq M, Troelsen JT, Boyd M, Eiberg H, Hansen L, Hussain MS, Rehman S, Azhar A, Ali A, Bakhtiar SM, Tommerup N, Baig SM, Kjaer KW
Title
Preaxial polydactyly/triphalangeal thumb is associated with changed transcription factor-binding affinity in a family with a novel point mutation in the long-range cis-regulatory element ZRS.
Are triphalangeal thumb-polysyndactyly syndrome (TPTPS) and tibial hemimelia-polysyndactyly-triphalangeal thumb syndrome (THPTTS) identical? A father with TPTPS and his daughter with THPTTS in a Thai family.
Sun M, Ma F, Zeng X, Liu Q, Zhao XL, Wu FX, Wu GP, Zhang ZF, Gu B, Zhao YF, Tian SH, Lin B, Kong XY, Zhang XL, Yang W, Lo WH, Zhang X
Title
Triphalangeal thumb-polysyndactyly syndrome and syndactyly type IV are caused by genomic duplications involving the long range, limb-specific SHH enhancer.
