The xeroderma pigmentosum group G (XPG) gene encodes an 1186-amino acid structure-specific endonuclease, known as XPG gene, which is an indispensable component of NER and belongs to the flap structure-specific endonuclease 1 (FEN1) family.5 This protein also has a role in other cellular processes, which is involved in the RNA polymerase II transcription and transcription-coupled DNA repair.8. The gene discussed is ERCC5; the disease is xeroderma pigmentosum.