The ERCC2 (excision repair cross-complementing rodent repair deficiency, complementation group 2) protein, which is also known as XPD, is involved in transcription-coupled nucleotide excision repair and is implicated in cancer-prone xeroderma pigmentosum, trichothiodystrophy, and Cockayne syndrome [28]. The gene discussed is ERCC2; the disease is trichothiodystrophy.