Dysplastic nevus syndrome: intrafamilial identification of carriers by cytogenetics.

Seven members of a family with dysplastic nevus syndrome (DNS) were examined clinically; skin biopsies of unaffected skin from 6 were taken. Biopsy-derived cultivated fibroblasts were examined by cytogenetic methods, i.e. by measuring the spontaneous and the UVB- and UVC-driven increase in sister chromatid exchange (SCE). A male patient with malignant melanoma, his son and his nephew, both with multiple dysplastic nevi, showed a distinctive elevation of UV-induced SCE, whereas the other, unaffected members of the family showed normal values. These results give evidence that in siblings with DNS the affected members can be identified not only on clinicopathological grounds but also by UV-induced elevated SCE at the cytogenetic level.