In terms of biological aging, ApoE4 expression is both a cause and consequence of mitochondrial dysfunction in the brain (Area-Gomez et al., 2020; Junxiang et al., 2020; Schmukler et al., 2020; Wynne et al., 2023), which is implicated in AD pathogenesis and in cellular senescence (Misrani et al., 2021; Miwa et al., 2022). The gene discussed is APOE; the disease is Alzheimer disease.