Using qPCR and two primers against the 5 ́and 3 ́ends of the XPG mRNA of we revealed an XPG-mRNA expression at control levels in cells from the severe CS case (Fig. 1D–E), but a significantly reduced mRNA expression in cells of the mildly affected CS and XP patients. The gene discussed is ERCC5; the disease is xeroderma pigmentosum.