Among these disorders are Cockayne syndrome which is caused by mutations in ERCC6 (CSB) or ERCC8 (CSA), trichothiodystrophy (TTD) caused by mutations in ERCC2 (XPD), ERCC3 (XPB), or TTDA (GTF2H5) and XPF-ERCC1 progeria (XFE) caused by dysfunction of the XPF-ERCC1 heterodimer [11,12]. The gene discussed is ERCC4; the disease is progeroid syndrome.