Xeroderma pigmentosum is a genetically heterogeneous autosomal recessive disorder characterized by increased sensitivity to sunlight with the development of carcinomas at an early age. Some patients develop neurologic symptoms or a more severe clinical phenotype known as de Sanctis-Cacchione syndrome. Xeroderma pigmentosum complementation group G (XPG) and XPG/Cockayne syndrome are caused by homozygous or compound heterozygous mutation in the ERCC5 gene. [From OMIM]