Abstract
It is known that deficiencies of the XPG gene cause a genetic disease of xeroderma pigmentosum (XP). In some cases with more destructive mutations of the gene, mixed symptoms of XP and a severe type of Cockayne syndrome (CS) were also found. Xpg-knockout mice show severe growth retardation and premature death as well as DNA repair defects, supporting the correlation between the severity of the gene mutation and severe-type CS association. However, the contribution of CS phenotypes is unclear in patients with less severe XPG mutations. We studied UVB-induced mutations in skin using lacZ-transgenic mice with a C-terminal truncation in both alleles of the Xpg gene which causes a mild DNA repair defect but not discernible growth deficiencies in affecting mice. We found a remarkable suppression of mutation induction in the skin epidermis from this mouse at higher UVB dose range.
