APOE and Alzheimer disease: In addition, the role of APOE in AD pathology is known to vary across ancestries.12,24,25,26 The levels of p-tau and total tau in African American individuals have been reported to be lower than those in European individuals,12,24,25,26 with a potential ancestry × APOE-ε4 interaction in AD pathology.27 This finding emphasizes the importance of considering ancestry in AD biomarker analyses.