Differences in the levels of UV repair and in clinical symptoms in two sibs affected by xeroderma pigmentosum.

UV-repair activity was studied in two sibs affected by XP showing different clinical symptoms. Complementation studies indicated that both patients fit into complementation group A. The levels of UV-induced 3H-thymidine incorporation, in fibroblasts and in lymphocytes, are different in the two patients: residual level of repair DNA synthesis in the sister is higher than in the brother. In one of the cell samples analyzed UDS analysis showed that in the sister a low proportion of cells with normal repair synthesis is present.