Deoxyuridine increases folate-sensitive fragile site expression in human lymphocytes

Deoxyuridine (dU) increases chromosome breakage at folic acid (FA)-sensitive common fragile sites (mostly 3p14 and 16q23) in human lymphocytes. This dU-related increase can be suppressed by thymidine or FA. These results suggest that the mechanism of fragile site expression in low FA medium involves misincorporation of dU into DNA.