Normal sensitivity to mutagens, spontaneous chromosome breakage, and mutation frequency in nevoid basal cell carcinoma syndrome.

Genetic instability in nevoid basal cell carcinoma syndrome (NBCCS) was investigated by measuring in lymphocytes obtained from four patients the level of UV-induced DNA repair synthesis, the DNA replication rate after treatment with different mutagens (UV light, mono- and bifunctional alkylating agents), the baseline mutation frequency, and the spontaneous chromosome breakage. All the parameters analyzed showed normal values; only the response to mitogens in NBCCS lymphocytes was delayed in comparison to that in normal donors. Our findings indicate that chromosomal instability and cellular UV hypersensitivity described in some NBCCS patients are not distinctive and constant features of NBCCS.