Our previous animal study supports the hypothesis by reporting that specific oligomeric Aβ (Aβ*56 and AβO) was existed in the olfactory epithelium at different progression stages of AD with evident cognitive impairment in AD transgenic mice; Tg2576, a Swedish mutant form of human amyloid precursor protein (APP) (KM670/671NL) (promoter: hamster prion protein (PrP))16. This evidence concerns the gene ABO and Alzheimer disease.