On the other hand, in non-familial, sporadic cases of AD mostly associated with late onset (LOAD), the ε4 allele of the apolipoprotein E (APOE) gene has been identified as a major genetic risk factor contributing to the pathogenesis of AD (Corder et al., 1993; Strittmatter et al., 1993). The gene discussed is APOE; the disease is Alzheimer disease.