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. 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, sparse appearance.
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. 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 of trichothiodystrophy. 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.