Apolipoprotein E (APOE), as the most important susceptible gene known, may play an important role in the predisposition to sporadic AD; the APOE4 gene is associated with late-onset AD and contributes to the development of neurofibrillary tangles and Aβ senile plaques (Corder et al., 1993; Poirier et al., 1993). Here, APOE is linked to Alzheimer disease.