Anyone who carries two copies of a certain gene is very likely to develop Alzheimer's. This predisposition could represent a new genetic form of Alzheimer's disease and adapted prevention and treatment approaches appear to be necessary for those affected.
A Spanish research team led by Dr. In a recent study, Juan Fortea from the Institut de Recerca Sant Pau demonstrated that people with two copies of the APOE4 gene (APOE4 homozygotes) have a more than 95 percent chance of developing biological signs of Alzheimer's. The corresponding study results are published in the specialist magazine “Nature Medicine”.
Genes as a cause of Alzheimer's?
Various factors such as diet and exercise have been proven to have a significant influence on the risk of Alzheimer's. However, there are also genetically determined forms of Alzheimer's in which the disease seems to be almost pre-programmed.
For example, mutations in the three genes APP, PSEN1 and PSEN2 can lead to the development of autosomal dominant early-onset Alzheimer's disease, which is clearly considered to be genetic and can occur from the age of 40, the researchers explain.
What role does APOE4 play?
The APOE4 gene has also been linked to a higher risk of developing Alzheimer's disease, and according to Dr. Fortea, the new study results now suggest that the presence of two copies of the APOE4 gene is also a separate genetic form of Alzheimer's disease.
For the study, the team used data from the National Alzheimer's Coordinating Center (USA) from 3,297 brain donors (273 of them APOE4 homozygotes) as well as clinical and biomarker data from over 10,000 people (including 519 APOE4 homozygotes) from five large multicenter cohorts (Europe and UNITED STATES).
Almost all showed signs of Alzheimer's
Data analysis showed that virtually all APOE4 homozygotes had Alzheimer's pathology and had higher levels of disease-associated biomarkers at age 55 than people with the APOE3 gene, the research team said.
By the age of 65, over 95 percent of APOE4 homozygotes had abnormal levels of amyloid in the cerebrospinal fluid, which is considered an important early pathological feature of Alzheimer's disease.
Up to three percent of the population affected
Based on these results, the researchers come to the conclusion that the genetic variant of the APOE4 gene is not only a risk factor for Alzheimer's disease, but could represent an independent genetic form of Alzheimer's disease.
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The study shows that virtually all people with this duplicate gene develop Alzheimer's. The researchers emphasize that this is an important finding because two to three percent of the population are APOE4 homozygotes.
New prevention and treatment approaches?
In their opinion, the insights gained could also be useful for future clinical studies as well as for the development of individualized prevention and treatment approaches for this specific population group.
In addition, the results underline the importance of monitoring APOE4 homozygotes from an early age in order to initiate preventive interventions if necessary, the research team concluded. (fp)
