The age‐specific cumulative penetrance, of Alzheimer's disease was computed in families for (a) APOE‐ε4 carriers, (b) APOE‐ε4 non‐carriers, (c) the highest and lowest PRS quintiles, (d) the highest and lowest PRS quintile among APOE‐ε4 allele carriers and (e) highest and lowest PRS quintiles among APOE‐ε4 non‐carriers. This evidence concerns the gene APOE and early-onset autosomal dominant Alzheimer disease.