ERCC3 and xeroderma pigmentosum: Mutations in TFIIH subunits that cause the inherited autosomal recessive disorders xeroderma pigmentosum (XP), trichothiodystrophy (TTD), and Cockayne syndrome (CS) are characterized by high incidence of cancer or premature ageing (Cleaver et al., 1999; Rapin, 2013).