DNA repair defects can cause an accelerated aging disease or an increased risk of cancer, or sometimes both.

[citation needed] Some examples of DNA repair defects causing progeroid syndromes in humans or mice are shown in Table 1.

Without reliable biomarkers of aging it is hard to support the claim that a disease condition represents more than accelerated mortality.

[42] Against this position other biogerontologists argue that premature aging phenotypes are identifiable symptoms associated with mechanisms of molecular damage.

[43] Such conditions, it is argued, are readily distinguishable from genetic diseases associated with increased mortality, but not associated with an aging phenotype, such as cystic fibrosis and sickle cell anemia.