This is not only of interest in CVD, but also in other diseases of ageing including Alzheimer disease, where the risk conferred by APOE ε4 is >5-fold greater than that seen in CVD, and age-related macular degeneration, where, in contrast to Alzheimer disease and CVD, ε2 confers an increase in risk of disease and ε4 confers a protective effect. The gene discussed is APOE; the disease is Alzheimer disease.