Analysis of apoE levels in Alzheimer’s disease patients and control subjects of APOE ε4 variant carriers and non‐carriers

Abstract Background Alzheimer’s disease (AD) is the most common progressive dementia disease in people over 60 years of age. The pathogenesis of AD is thought to be complex and depends on environmental and genetic factors. The most important genetic factors responsible for AD include variants of the APOE gene, which encodes the protein apolipoprotein E (apoE). There are 2 polymorphisms in the APOE, which presence of three alleles: protective ‐ ε2, neutral ‐ ε3, and pathogenic ‐ ε4. On the other hand, the presence of the ε4 allele is associated with an approximately four times higher risk of developing AD in people with a heterozygous system and a twelve times higher risk in ε4/4ε. Disorders of epigenetic mechanisms affecting the concentration of apoE may participate in the development of AD. Disturbed levels of apoE may impair clearance of Aβ from the brain and exacerbate disease progression. It is not known what level of apoE ensures the removal of Aβ and whether genetic and familial predispositions can regulate the efficiency of protective mechanisms. So far, there is little information on the level of apoE in AD patients and controls who are and are not APOE ε4 carriers. The aim was to analyze genetic variants of the APOE gene and apoE protein concentration in AD patients, control subjects related to AD cases (CR), and controls subjects without a family history of AD (CU), carriers and non‐carriers of the APOE ε4 variant. Method The studies were conducted on 156 individuals (AD and controls). The APOE genotype was determined by real‐time PCR. The apoE concentration was determined by the ELISA method. Result The highest concentration of apoE was found in CR compared to AD and CU (p<0.001). In both APOE ε4 carriers (p<0.05) and non‐carriers (p<0.001), the highest levels of apoE were found in CR. At the same time, in all tested subjects, carriers of APOE ε4, the level of apoE was lower compared to non‐carriers of this pathogenic variant. Conclusion It seems that the ε4 pathogenic variant of the APOE gene may lead to the development of AD by regulating the level of apoE.