OBSOLETE: Xeroderma pigmentosum complementation group G

Xeroderma pigmentosum complementation group G (XP-G) is a rare autosomal recessive disorder caused by mutations in the ERCC5 (XPG) gene, which encodes a structure-specific endonuclease essential for nucleotide excision repair (NER) of UV-induced DNA damage. This Orphanet entry (276267) is designated as OBSOLETE, meaning it has been retired and its clinical content has been merged into or replaced by other active entries for xeroderma pigmentosum. Patients previously classified under this code are now typically referenced under the broader xeroderma pigmentosum group G entity. XP-G affects primarily the skin, eyes, and in some cases the neurological system. Affected individuals develop extreme sensitivity to ultraviolet (UV) radiation, leading to severe sunburns, freckling, and a dramatically increased risk of skin cancers (basal cell carcinoma, squamous cell carcinoma, and melanoma) at a very young age. Ocular manifestations include photophobia, keratitis, and conjunctival inflammation. A subset of patients with XP-G also develop progressive neurological degeneration, including sensorineural hearing loss, diminished deep tendon reflexes, and cognitive decline. Some severe mutations in ERCC5 can also cause a combined XP/Cockayne syndrome phenotype with growth failure and additional neurological features. There is no cure for XP-G. Management centers on rigorous UV protection, including protective clothing, UV-filtering eyewear, and avoidance of sunlight exposure. Regular dermatological surveillance with early detection and removal of premalignant and malignant skin lesions is critical. Neurological symptoms are managed supportively. Genetic counseling is recommended for affected families.

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