This finding raised the hypothesis that other unappreciated risk factors are involved in the pathogenesis of the disease, such as apolipoprotein E (apoE=protein, APOE=gene) since the APOE4, one of the APOE coding-alleles, has a strong association with late-onset Alzheimer’s disease. The gene discussed is APOE; the disease is early-onset autosomal dominant Alzheimer disease.