Trichothiodystrophy
Pronunciation: trik-oh-thy-oh-DIS-troh-fee
A rare autosomal recessive multisystem disorder in which sulfur-deficient, brittle hair is the hallmark feature, frequently accompanied by photosensitivity, ichthyosis, and neurodevelopmental delay in children.
Full Definition
Trichothiodystrophy (TTD) is caused by mutations in nucleotide excision repair pathway genes (most commonly ERCC2/XPD), resulting in deficient incorporation of cysteine-rich matrix proteins into the hair shaft. The characteristic finding on polarising microscopy is a 'tiger-tail' banding pattern of alternating light and dark bands. Clinical features vary widely and are summarised by the mnemonic PIBIDS (photosensitivity, ichthyosis, brittle hair, intellectual impairment, decreased fertility, short stature). In pediatric dermatology manuscripts, TTD is often contrasted with xeroderma pigmentosum because of shared DNA repair defects but differing cancer risk. Editors working on these texts must preserve technical hair-morphology descriptors accurately.
Usage
Usage note: TTD is an acceptable abbreviation after first use. Do not confuse with xeroderma pigmentosum despite shared repair gene mutations; TTD has low skin cancer risk.
In Context
- "Polarising light microscopy revealing 'tiger-tail' banding confirmed the diagnosis of trichothiodystrophy in the 18-month-old patient." — Pediatric dermatology diagnostic report
- "The manuscript incorrectly used 'trichorrhexis nodosa' where 'trichothiodystrophy' was the confirmed diagnosis; editors must verify these distinct structural hair disorders are not interchanged." — Peer-review editorial feedback