Deoxyuridine increases folate‐sensitive fragile site expression in human lymphocytes

Abstract
Deoxyuridine (dU) increases chromosome breakage at folic acid (FA)‐sensitive common fragile sites (mostly 3pl4 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.