In Alzheimer’s disease (AD), the three APOE variants (ε2, ε3, and ε4) have been consistently associated with disease risk, making it the strongest single-gene predictor at a population level in neuropsychiatry. However, additional risk variants summarised in a PRS improve the prediction model further. For example, Desikan et al. [61] showed that amongst APOE ε3/3 carriers, PRS modified the expected age of AD onset by more than 10 years between the lowest and highest deciles (hazard ratio 3.34, p = 10−22).
