Mutations cause Cockayne syndrome, which is characterized by severe growth defects, mental retardation, and cachexia.

Mutational defects in the Ercc5(Xpg) gene can cause either the cancer-prone condition xeroderma pigmentosum (XP) alone, or in combination with the severe neurodevelopmental disorder Cockayne syndrome (CS) or the infantile lethal cerebro-oculo-facio-skeletal syndrome.

[8] An Ercc5(Xpg) mutant mouse model presented features of premature aging including cachexia and osteoporosis with pronounced degenerative phenotypes in both liver and brain.

[8] These mutant mice developed a multi-system premature aging degenerative phenotype that appears to strengthen the link between DNA damage and aging.

[9] Dietary restriction of the mutant mice, while delaying aging, also appeared to slow the accumulation of genome wide DNA damage and to preserve transcriptional output, thus contributing to improved cell viability.