ERCC5 and Cockayne syndrome: Mutations in XPG lead to two autosomal recessive genetic disorders, xeroderma pigmentosum (XP) and Cockayne syndrome (CS) (Berneburg and Lehmann, 2001; Bootsma et al., 1995; Fassihi et al., 2016; Lehmann et al., 2018; Okinaka et al., 1997; Scharer, 2008).