When disturbed, it increases the risk of neurological disease, as strikingly demonstrated by the association of the apolipoprotein E (ApoE) allele ε4 (APOE ε4) with late-onset AD (Strittmatter et al., 1993; Kawade and Yamanaka, 2024; Yang et al., 2023). The gene discussed is APOE; the disease is nervous system disorder.