Xeroderma pigmentosum complementation group E: a case report.

A 5-year-old female Japanese patient with mild symptoms of xeroderma pigmentosum (XP), XP7OTO, was assigned to complementation group E following cell hybridization. XP7OTO showed lowered minimal erythema doses compared with those of normal Japanese and XP group A subjects at 290 and 300 nm of monochromatic ultraviolet (UV) light. The delayed peak reaction of UV erythema was characteristically observed in this particular group E patient. 254 nm UV-induced unscheduled DNA synthesis of XP7OTO skin fibroblasts was reduced to a level of 55% of normal. XP7OTO cells exhibited a twice higher sensitivity to 254 nm UV killing (n (extrapolation number) = 1.2, Do (mean lethal dose) = 2.2 J/m2) than did normal cells (n = 1.5, Do = 5.0 J/m2). The patient has, as yet, developed neither skin malignancies nor neurological abnormalities.