APOE and Alzheimer disease: Metabolic pathways that differed between APOE4 and APOE3 mice in our study are affected by AD or APOE genotype in other tissues, including those involved in amino acid metabolism, oxidative phosphorylation, and sirtuin signaling (Yin et al., 2018; Haytural et al., 2021; Toledo et al., 2017; Valla et al., 2010).