trichothiodystrophy

Congenital brittle hair resulting from low sulfur-containing amino acid (cysteine) content sometimes associated with mental impairment and short stature; autosomal recessive inheritance. [tricho- + thio- + G. dys, bad, + trophe, nourishment]

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tricho·thio·dys·tro·phy (trik″o-thi″o-disґtrə-fe) any of several autosomal recessive disorders in which hair is sparse and brittle, has an unusually low sulfur content, and has a banded appearance under polarized light; ichthyotic skin and physical and mental retardation are also present. The disorders are categorized on the basis of whether photosensitivity is also present; the photosensitive form is caused by mutations affecting either subunit of a DNA helicase involved in transcription and nucleotide excision repair; there are multiple nonphotosensitive forms caused by varying mutations.