New Clinico-Genetic Classification of Trichothiodystrophy

Trichothiodystrophy (TTD) was identified as a congenital hair disorder with autosomal recessive transmission, characterized by specific hair shaft abnormalities and associated with various neuroectodermal symptoms. The study involved 9 patients from the authors' institution and reviewed 79 others with molecular analysis from a total of 122 reported cases. It found that photosensitive forms of TTD were linked to mutations in genes encoding subunits of the transcription/repair factor IIH (TFIIH), while 10% of non-photosensitive patients had TTDN1 mutations. The study noted a higher frequency of congenital ichthyosis in the TFIIH mutated group and more frequent hypogonadism in the non-photosensitive group. The authors proposed a new clinico-genetic classification to aid clinicians and suggested that understanding the TTD ichthyotic phenotype could lead to therapeutic advances.