Trichothiodystrophy: Current Concepts

Trichothiodystrophy (TTD) was identified as a rare autosomal recessive disorder characterized by sulfur-deficient brittle hair and a defect in the excision repair of ultraviolet damage in fibroblasts. The study categorized TTD patients into three groups based on genetic defects: those with ERCC2 (XP-D), ERCC3 (XP-B), and a distinct repair defect. Unlike xeroderma pigmentosum (XP) patients, TTD patients did not exhibit an increased frequency of skin cancers. The research highlighted that the ERCC2 gene, part of the TFIIH complex, played a role in both transcription initiation and nucleotide excision repair. The primary defect in TTD was in transcription initiation, whereas in XP-D, DNA repair was primarily affected.