The available scientific literature within the last decade (2008–2018) was searched in the Thomson Reuters ISI Web of Knowledge, Science Direct, PubMed and Google Scholar databases by combining at least two of the following keywords: biosensor/electrochemical immunosensor/optical immunosensor/DNA sensor in conjunction with Alzheimer’s disease/Amyloid beta/Tau protein/Apolipoprotein E. The gene discussed is APOE; the disease is Alzheimer disease.