APOE and Alzheimer disease: Several studies of Alzheimer’s disease in Han Chinese populations have confirmed a link between Alzheimer’s disease and APOE genotype [20,21], however the prevalence of the APOE ε4 allele among those diagnosed with Alzheimer’s disease has been found to vary substantially across geographic regions [22], suggesting that APOE genotype may be a more important determinant of Alzheimer’s disease risk among certain populations.