Report of three sisters with XP-E, a rare xeroderma pigmentosum complementation group.

Three sisters with a rare complementation group of classical xeroderma pigmentosum (XP-E) are presented. The patients developed sun-sensitivity and dyspigmentation between the ages of 6 and 9 years and UV-induced skin tumors between 16 and 20. All malignant skin tumors were basal cell carcinomas; no other skin tumors have been diagnosed so far. Measurement of UV-induced unscheduled DNA synthesis in cultivated fibroblasts showed very high residual repair levels: 60 to 70% of controls. In fusion experiments with representative cell strains complementation was found with the XP-A, B, C, D and G complementation group but it was absent when the fibroblasts under study were fused with XP-E group fibroblasts. Thus the cell lines were assigned to the XP complementation group E.