Furthermore, subgroup analysis stratified by ethnicities and APOE ε4 was performed and showed no obvious difference (Ethnicity: p = 0.1; APOE ε4: p = 0.55), implying that the ethnicity and APOE ε4 exerted no influence on the association between the 5HT2A C102T polymorphism and risk of AD. This evidence concerns the gene APOE and Alzheimer disease.