Trichothiodystrophy, a transcription syndrome

Trends Genet. 2001 May;17(5):279-86. doi: 10.1016/s0168-9525(01)02280-6.


Trichothiodystrophy (TTD) is a rare genetic disorder characterized by a hair dysplasia and associated with numerous symptoms affecting mainly organs derived from the neuroectoderm. About half of TTD patients exhibit photosensitivity because their nucleotide-excision repair pathway (NER) does not remove UV-induced DNA lesions efficiently. However, they do not present the skin cancer susceptibility expected from such an NER disorder. Their deficiencies result from phenotype-specific mutations in either XPB or XPD. These genes encode the helicase subunits of TFIIH, a DNA repair factor that is also required for transcription of class II genes. Thus, time- and tissue-specific impairments of transcription might explain the developmental and neurological symptoms of TTD. In a third group of photosensitive patients, TTD-A, no mutation has been identified, although TFIIH amount is reduced.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Abnormalities, Multiple / genetics*
  • DNA Helicases*
  • DNA Repair / genetics*
  • DNA-Binding Proteins / genetics
  • Hair Diseases / genetics*
  • Humans
  • Ichthyosis / genetics
  • Neurocutaneous Syndromes / genetics
  • Phenotype
  • Photosensitivity Disorders / genetics*
  • Proteins / genetics
  • Transcription Factor TFIIH
  • Transcription Factors / genetics
  • Transcription Factors, TFII*
  • Transcription, Genetic / genetics
  • Ultraviolet Rays
  • Xeroderma Pigmentosum Group D Protein


  • DNA-Binding Proteins
  • Proteins
  • Transcription Factors
  • Transcription Factors, TFII
  • XPBC-ERCC-3 protein
  • Transcription Factor TFIIH
  • DNA Helicases
  • Xeroderma Pigmentosum Group D Protein
  • ERCC2 protein, human