ERCC4 and XFE progeroid syndrome: XFE progeroid syndrome results from mutations in ERCC4/FANCQ causing reduced expression of XPF-ERCC1, a heterodimeric DNA repair endonuclease required for NER, DNA ICL repair, and the repair of some DNA DSBs (Niedernhofer et al., 2006; Ahmad et al., 2008; Bhagwat et al., 2009).