Alzheimer's disease as a neurodegenerative disorder and the apolipoprotein E gene as its genetic biomarker

Alzheimer's disease (AD) is a progressive brain disorder that slowly destroys memory and thinking and functional skills. Alzheimer's disease is classified into two familial and sporadic types. Alzheimer's disease is also divided into the early or late onset of symptoms, with early-onset before age 65 and late-onset after this age. Symptoms of this disease appear in 4 stages: pre-dementia, early, middle and advanced. Many factors are involved in the pathophysiology of this disease. These include oxidative stress, inflammation, and genetics. Oxidative stress occurs with the involvement of beta-amyloid in mitochondrial function. Inflammation also results from the release of beta-amyloid in the brain and the release of inflammatory cytokines. The genes APP, presenilin 1, presenilin 2, and apolipoprotein (ApoE) play a key role in Alzheimer's disease. Due to the important role of the ApoE gene in this disease, common varieties and mutations of this gene can be considered as potential biomarkers of AD. This aimed to review study was to describe the characteristics of Alzheimer's disease and also to introduce the ApoE gene as a biomarker of this disease.