ERCC4 and Friedreich ataxia: Rare mutations in ERCC1 and ERCC4/XPF, encoding the NER 5’-endonuclease, may cause complicated features beyond XP, CS, and TTD, including Cerebro-Oculo-Facio-Skeletal Syndrome (COFS) (42), Fanconi anemia (FA) (43, 44), XFE-progeroid syndrome (XFE) (45), XP-CS-FA (44), and ERCC1-hepatorenal syndrome (46).