ERCC4 and xeroderma pigmentosum: Xeroderma pigmentosum (XP) is a rare autosomal recessive disorder caused by changes in the DNA repair pathway related to variants in eight genes, and it is clinically recognized as XPA, XPB, XPC, XPD, XPE, XPF, XPG, and XPV (Digiovanna & Kraemer, 2012; Fassihi, 2013; Gruener & Morley, 2018).