APOE and Alzheimer disease: For example, in a study of the association between the LIPC rs493258 polymorphism and the risk of macular degeneration [23], the terms “stratified analysis” and “stratification” were used to describe a subgroup method; however, in the original publication of the study on the relationship of the VEGF rs157036 polymorphism with AD risk, a subgroup analysis of ApoE ε4 status was mistaken for a stratified analysis [12].