Is this theoretically possible using genetic engineering?

Okay, this is just a theoretical question but I just had to get some opinions. According to the DNA damage thory of aging, we age because our DNA acquires irrepairable damage and mutations over time. If this is true would a DNA sample of a person, say in their twenties, be used to track what parts of their DNA have been damaged or mutated when they are much older? If so, could this sample be even used to repair the damage by reintroducing it into the DNA using gene therapy or some other process?