APOE and Alzheimer disease: With converging evidence demonstrating a number of well-established common genetic variants contribute to risk for Alzheimer’s disease (AD), which have impact en masse comparable to the established APOE ε4 allele risk factor [30], an individuals’ genetic risk score (polygenic risk score; PRS) provides a stable indicator of risk across the lifespan, useful for informing preclinical models, antecedent to symptoms.