HTR2A and Alzheimer disease: In addition, subgroup analysis stratified by APOE ε4 revealed that the distributions of allelic contrast (OR = 1.44; 95% CI = 1.05–1.99) and dominant model (OR = 2.49; 95% CI = 1.46–4.25) of 5HT2A C102T were significantly increased in AD subgroup without APOE ε4, but not in AD subgroup with APOE ε4 (p > 0.05) (Table 2).