[Trichothiodystrophy. Hair examination as a diagnostic tool].

Trichothiodystrophy is a neuroectodermal syndrome with features of a specific hair dysplasia associated with disorders in organs derived from ectoderm and neuroectoderm. The key finding is brittle hair with low sulfur content. Polarizing microscopy shows alternating dark and light bands with trichoscisis and absent or defective cuticle. Patients with trichothiodystrophy have short, sparse, dry and easily broken hair. Growth retardation and mental retardation are almost obligatory findings. The skin and the nails are very often affected; other neuroectodermal disorders are associated, but none is a constant feature. The disease is transmitted as an autosomal recessive trait.