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TrichoThioDystrophy Photosensitive (TTDP)

Can be caused by mutation in at least 2 separate genes: ERCC2 (XPD) and ERCC3 (XPB), which encode the 2 helicase subunits of transcription/repair vector TFIIH. Most patients carry mutations in XPD; mutations in XPB concern only a few patients. Besides XP groups B and D, an exceptional trichothiodystrophy complementation group designated TTD-A was identified in 1993. This form was found by Giglia-Mari et al. (2004) to be caused by mutation in the tenth subunit of TFIIH, TFB5.

Trichothiodystrophy or TTD, as it is concisely mentioned, is a heterogeneous group of autosomal recessive disorders, characterized by abnormally sulfur deficient brittle hair and accompanied by ichthyosis and other manifestations. In TTD patients, the hair appear dry, short and sparse, and the ones already existing splits longitudinally in to small fibers, the viscoelastic parameters of hair being compromised compared to controls.  
Inside the range of TTD syndrome are numerous interrelated neuroectodermal disorders. The Trichothiodystrophy syndromes are invariably characterized by the defective synthesis of high-sulfur matrix proteins. Half of the patients show abnormalities in nucleotide excision repair (NER) of ultraviolet damaged DNA. 

OTHER NAME(S): ICHTHYOSIFORM ERYTHRODERMA WITH HAIR ABNORMALITY AND MENTAL AND GROWTH RETARDATION
TAY SYNDROME
TRICHOTHIODYSTROPHY WITH CONGENITAL ICHTHYOSIS
ICHTHYOSIS, CONGENITAL, WITH TRICHOTHIODYSTROPHY
IBIDS SYNDROME

ABREVIATION(S):
TTD

Related patway(s): nucleotide excision repair (NER), transcription factors

DNAtraffic protein(s) related to disease: ERCC3 (XPB), ERCC2 (XPD)

OMIM: 601675

Last modification date: July 30, 2011