Protective effect of S-adenosylmethionine against the induction of chromosome fragile sites.

Chromosome fragile sites were induced in the peripheral lymphocytes of 7 donors by treatment of the cells in culture with 5-fluorodeoxyuridine and caffeine. The appearance of these fragile sites was inhibited to a large extent and in a dose-dependent manner by S-adenosylmethionine. It is possible that this methyl donor exerted its protective action through restoration of the correct level of methylation of the DNA.