The loss of a DNA base causes an abasic site
Hydrolysis of the deoxyribose Cl'–base linkage results in the complete loss of a purine or pyrimidine base, resulting in what is called an abasic site, an event with obvious genetic consequences. This hydrolysis reaction is much more likely to occur at purine bases, resulting in depurination of the DNA (Table 3a). Loss of DNA bases occurs only slowly at normal physiological pH and temperatures, but the large number of bases in the genome of a cell (6.2 × 109 in the case of human cells) means that many thousands of individual events occur each day in every cell. This hydrolysis is also the reason why the DNA within dead tissues gradually loses its integrity, limiting our ability to analyse and manipulate DNA from preserved tissues.