MUTATIONS THAT DISABLE THE DNA-REPAIR GENE XPG IN A XERODERMA-PIGMENTOSUM GROUP-G PATIENT

The human XPG (ERCC5) gene encodes a large acidic protein that corrects the ultraviolet light sensitivity of cells from both xeroderma pigmentosum complementation group G and rodent ERCC group 5. Here we characterize five XPG sequence alterations and a minor splicing defect in XP-G patient XP125LO. Three of these changes are polymorphic variants whereas the remaining two, one in each XPG allele, inactivate complementation in vivo. These single point mutations provide formal proof that defects in XPG give rise to the group G form of xeroderma pigmentosum, and their locations suggest ways in which this may occur.