A new study finds that possessing two copies of a specific gene mutation that’s common in Alzheimer’s disease may be the cause behind the disease in those people.
Previously, researchers knew that the gene raised people’s risk for the disease. The study, published on Monday in Nature Medicine, showed that about 15% of Alzheimer’s patients carry two copies of APOE4. Those cases “can be tracked back to a cause and the cause is in the genes,” Fortea said in an Associated Press article.
Symptoms can begin seven to 10 years sooner in people with the gene mutations compared to other older adults who develop Alzheimer’s (most cases start after people turn 65). Juan Fortea, PhD, one of the researchers and director of the Memory Unit at the Sant Pau Research Institute’s Neurology Service in Barcelona, Spain, said in a statement that having two copies of the APOE4 is a new genetic form of Alzheimer’s disease.
“This gene has been known for over 30 years and it was known to be associated with a higher risk of developing Alzheimer’s disease. But now we know that virtually all individuals with this duplicated gene develop Alzheimer’s biology,” Fortea said in a statement.
“This is important because they represent between 2 and 3% of the population,” he added.
As part of the study, the team assessed data from nearly 3,300 brain donors, including samples from 273 people with two copies of the APOE4 gene.
People with two copies of the APOE4 gene had higher levels of brain changes linked to the disease at age 55 compared to people with another version of APOE, the researchers found. More than 95% of people with two APOE4 genes showed abnormal levels of amyloid protein in their cerebrospinal fluid, and 75% had positive amyloid scans by the age of 65, the team noted. Amyloid beta plaques are a symptom of Alzheimer’s.
The team also evaluated clinical data from more than 10,000 people who demonstrated evidence of Alzheimer’s disease, including 519 people with two copies of APOE4.
“The data clearly show that having two copies of the APOE4 gene not only increases the risk, but also anticipates the onset of Alzheimer’s, reinforcing the need for specific preventive strategies,” Alberto Lleó, PhD, director of the Sant Pau Research Institute’s Neurology Service, said in the same statement.
People with two copies of APOE4 should be studied more in clinical trials, as they’re almost certain to develop Alzheimer’s. The people would be ideal targets for prevention and treatment methods, the team said.
