HYPERSENSITIVITY TO G2 CHROMATID RADIATION DAMAGE IN FAMILIAL DYSPLASTIC NAEVUS SYNDROME

Abstract Skin fibroblasts from 25 members of nine kindreds with familial dysplastic naevus syndrome (DNS), 12 apparently normal spouses, and 11 additional unrelated normal individuals were tested for G 2 cell-cycle phase sensitivity to ionising radiation. The cells from individuals with DNS or hereditary cutaneous malignant melanoma with DNS (HCMM/DNS) had significantly more chromatid breaks and gaps when entering metaphase 0.5-1.5 h after G 2 phase X-irradiation (1 Gy) than those from unaffected controls. In two cases, the test results positively identified individuals before the clinical diagnosis of DNS. A clinically normal obligate carrier of the HCMM/DNS gene showed the enhanced G 2 radiosensitivity. Moreover, in a test on 1 proband, the sensitivity was apparent in peripheral blood lymphoblasts. Enhanced G 2 chromatid radiosensitivity may be a marker of genetic susceptibility to HCMM/DNS.