1990 Volume 52 Issue 2 Pages 279-284
Sib patients bearing basaliomas with xeroderma pigmentosum (XP), XP90TO (42 yr, male) and XP92TO (40 yr, female), were assigned to group F by a complementation analysis in heterodikaryons. Clinically, both patients manifested from moderate to severely acute sun-sensitivity by the age of 8, pigmented freckles by age 10, and skin malignancies in their forties (6 basaliomas at 42 yr in XP90TO; 1 basalioma at 41 yr in XP92TO). The patients were not consanguieous. Despite the still currently sunsensitive state, the patients showed a normal minimal erythema dose (MED) at wavelengths of 290, 300 and 305 nm but abnormally delayed peaking of erythema rection after 48 h after exposure. The XP90TO and XP92TO fibroblasts exhibited typical XP-F characteristics of a higher sensitivity at 3 times the lethal effect of 254 nm ultraviolet light (UV) (n (extrapolation number)=1.1, Do (mean lethal dose)=1.7 J/m2) as well as a reduced level of 12% unscheduled DNA synthesis (UDS), compared to normal cells (n=1.5, Do=5.0 J/m2).
