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trichothiodystrophy (TTD)
Pathology:
- cells from individuals with photosensitive TTD have defects in nucleotide excision repair indistinguishable from cells obtained from patients with Xeroderma Pigmentosum (XP)
- tiger tail banding of hair strands [2]*
* image [2]
Genetics:
1) autosomal recessive
2) associated with defects in GTF2H5 gene
3) associated with defects in TTDN1 gene (non-photosensitive)
4) associated with defects in ERCC2, ERCC3 (photosensitive)
Clinical manifestations:
1) sulfur-deficient brittle hair
2) small size, impaired sexual development
3) mental retardation
5) unusual facial features
6) photosensitivity (frequent)
7) ichthyosis (fish-like scales on skin)
a) neonates with trichothiodystrophy & ichthyosis are usually born with a collodion membrane
b) severity of the ichthyosis after the membrane is shed is variable, ranging from a mild to severe
8) newborn withe frizzy hair, low set ears [2]*
* image [2]
Complications:
- individuals with TTD do not appear to have an increased risk of malignant neoplasms
Related
nucleotide excision repair
General
dwarfism (nanism)
progeroid syndrome
References
- Lehmann AR.
Nucleotide excision repair and the link with transcription.
Trends Biochem Sci. 1995 Oct;20(10):402-5. Review.
PMID: 8533152
- Garon L, Kokta V, Coulombe J.
Images in Dermatology
Trichothiodystrophy
JAMA Dermatol. 2023;159(8):877
PMID: 37342013
https://jamanetwork.com/journals/jamadermatology/fullarticle/2806332
Databases & Figures
OMIM correlations
Human Disorders of DNA Repair