The significant differences in APOE ε4 allele frequency and Aβ positivity between SMC and CI groups in both ADNI-2 and ADNI-3 cohorts (Table 2) confirm APOE ε4 as a major genetic risk factor for Alzheimer’s disease (AD) and highlight the association between Aβ pathology and cognitive decline. The gene discussed is APOE; the disease is early-onset autosomal dominant Alzheimer disease.