A group of hereditary diseases inherited as autosomal recessives in which the skin is extremely sensitive to sunlight or ultraviolet light, and death is usually due to skin cancer. Normal skin cells can repair UV damage to DNA by cut-and-patch repair (q.v.). Skin cells from patients with xeroderma pigmentosum contain mutations in genes functioning in this process. For example, the XPA gene at 9q encodes a DNA-binding protein that recognizes damaged regions. Helicases encoded by XPB (2q) and XPD (19q) unwind the double helix and expose these damaged segments. Endonucleases encoded by XPG (13q) then cut out the defective segments. See Chronology, 1968, Cleaver. http://www.xps.org.
Subjects: Genetics and Genomics — Medicine and Health.