Trichothiodystrophy is a congenital disorder that involves production
of abnormal, brittle hair. The hair complications are usually only
part of the disease. Frequently, trichothiodystrophy also involves
problems with hair related structures such as the teeth, eyes (cataracts)
and nails (onchodystrophy). It can also involve stunted growth,
mental retardation, skin sensitivity to light and skin ichthyosis.
There are several different forms of trichothiodystrophy and occasionally
some individuals are reported as having the brittle hair symptom
but without any other symptoms.
Brittle hair is one of the diagnostic markers for trichothiodystrophy.
The individual has what looks like sparse short hair growth over
the scalp and elsewhere on the body. Under the microscope the hair
can be seen to have a squashed oval shape in cross section, an irregular
diameter along its length, has abnormal or no cuticle, and with
abnormal irregular pigment incorporation along its length. Where
trichothiodystrophy is suspected, hair samples are often tested
for sulfur content and cysteine amino acid content. Trichothiodystrophy
affected hair has only around 50% of the sulfur and cysteine content
found in normal hair.
The hair follicles of trichothiodystrophy affected individuals
are all fully functioning but the hair is so brittle that once it
emerges from the skin and becomes exposed to the environment trichorrhexis
nodosa, trichoclasis, and trichoschisis occur in the hair fibers.
The breakage and fracturing in the brittle hair result in the short,
Treatment is very difficult as trichothiodystrophy is a genetic
disease. It seems that the genes for processing and utilizing sulfur
in the body are not functioning properly. Some recent research suggests
that defects in xeroderma pigmentosum group D (XPD) protein gene
can lead to trichothiodystrophy, but this is not the whole story.
While some individuals with trichothiodystrophy have photosensitivity,
like people with xeroderma pigmentosum, not all do. Most likely
there are several gene defects that can lead to the development
There is no form of gene therapy available now or in the foreseeable
future for trichothiodystrophy. Treatment usually involves preventative
measures, avoiding excessive hair styling and exposure to light.
Some dermatologists also attempt to use cysteine amino acid supplementation
in the diet.
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