Trichothiodystrophy: Molecular insights and mechanisms of pathogenicity.

Trichothiodystrophy (TTD) is a rare hereditary disease characterized by brittle, sulphur deficient hair associated with a wide and varied spectrum of clinical features which include skin alterations, neurodevelopmental defects, and immune dysfunction. The presence of hypersensitivity to UV light defines the two main forms of TTD: photosensitive (PS-TTD) and non-photosensitive (NPS-TTD). The disease arises from mutations in a variety of genes involved in different biological processes. Affected processes include DNA repair, transcription as well as translation. This review provides the latest vision of TTD: from up-to-date mutational spectra and genotype-phenotype relationships to our current understanding of the pathogenic mechanisms that underlie the complex etiology of this multi-faceted disease.