Cell type-dependent difference in the distribution and frequency of excess thymidine-induced common fragile sites: T lymphocytes and skin fibroblasts.

Common fragile sites were induced by excess thymidine in phytohemagglutinin-stimulated T lymphocytes from 4 normal individuals, and skin fibroblasts from 4 normal and 5 fra(X) positive individuals. The results indicate that the frequency and distribution of excess thymidine-induced fragile sites are different between these two types of cells. The sites at 1p13 and 2p11.2, induced in both types of cells, have not previously been described, and are thus considered to be excess thymidine-specific fragile sites. These findings extend and support our previous studies on cell type-dependent difference in aphidicolin-induced common fragile sites.