 Damage to mtDNA is therefore another contributing factor to phenotypes related to aging.Neurodegeneration and cancer are two factors that manifest with DNA damage; therefore, we need to understand the change in the association between DNA damage and DNA repair as we age in order to be aware of age-related diseases and develop lifestyles that could possibly promote a healthy life span.The DNA damage theory of aging postulates that DNA damage is ubiquitous in the biological world and is the primary cause of ageing.