The most common type of Alzheimer’s disease usually begins after age 65 (late-onset Alzheimer’s disease, LOAD), which has been related to predisposing environmental factors such as diet, smoking, drinking alcohol in excess, low physical and mental activity, allelic predisposition by apolipoprotein E (APOE), and the triggering receptor expressed in myeloid cells; moreover, age is the main risk factor for developing AD. The gene discussed is APOE; the disease is early-onset autosomal dominant Alzheimer disease.