Skin cancer and chromosomal aberrations induced by ultraviolet radiation. Evidence for lack of correlation in xeroderma pigmentosum variant and group E patients.

Ultraviolet radiation (UV) in sunlight induces an abnormally high incidence of skin cancer in patients with xeroderma pigmentosum (XP), an autosomal recessive disease with defects in the repair of damaged DNA. We determined the frequency of UV-induced chromosomal aberrations in cultured lymphoblast lines from a patient with the variant form of XP, from a patient with the complementation group E form, and from two patients with the complementation group C form. In contrast to results with patients having other forms of XP, the group E and variant patients showed no abnormal increase in UV-induced chromosomal aberrations. Even in the presence of caffeine, which exacerbates the postreplication repair defect of UV-irradiated XP variant cells, there was still no abnormally elevated frequency of UV-induced chromosomal aberrations in the variant cells. These results, indicating that the level of UV-induced chromosomal aberrations is not correlated with these patients' marked susceptibility to skin cancer, suggests that some mechanism other than genetic transposition is causatively related to these XP patients' high incidence of sunlight-induced skin cancer.