Experimental and human population studies of DNA lesions in healthy individuals

DNA damage is a valuable biomarker in human molecular epidemiology being associated with many diseases. However, the level of DNA damage is influenced also by intrinsic features of healthy persons: heredity, sex, age and body type. The objective of this review was to summarize data on DNA breakage level in healthy humans depending on their characteristics and to compare these data with experimental studies and observations on animals dealing with the same factors. Several strains of laboratory animals manifest an increased level of DNA breaks. In humans some gene polymorphisms are associated with [an] increased level of DNA damage, however it is believed that environmental factors are more important. In animals a higher level of DNA breakage is usually detected in males. In humans data on the role of gender are contradictory and depend on race. Experimental models provide evidence of increased levels of single- and double-strand breaks in obese animals. Human studies are not so convincing, an increase of double-strand breaks appears to be a more reproducible feature of DNA of overweight persons. Data on single-strand DNA breaks in aged persons are contradictory, but double strand breaks evidently increase with age.