Researchers of a study have revealed that individuals with two copies of the APOE4 gene variant are almost certain to develop Alzheimer’s disease if they live long enough, suggesting that this genetic configuration is not just a risk factor but a distinct form of Alzheimer’s disease. Researchers from Spain and the United States found that 95% of people over 65 with two copies of APOE4 had Alzheimer’s disease biomarkers in their cerebrospinal fluid, indicating that APOE4 homozygosity could be considered a genetic form of the disease.

The study, which analyzed over 13,000 people, also found that APOE4 homozygotes begin to show symptoms around age 65, about 10 years earlier than those with other APOE variants. The findings suggest that APOE4 homozygotes have a pattern of biomarker changes similar to those seen in early-onset Alzheimer’s disease and down syndrome-related Alzheimer’s disease, rather than the sporadic late-onset form typically associated with one copy of APOE4. If APOE4 homozygosity is reclassified as a genetic form of Alzheimer’s disease, it could lead to changes in how clinical trials are conducted and influence the development of preventive interventions for millions of people.

Reference: Dyer R. New Genetic Form of Alzheimer’s Identified in People With Common Risk Factor. Science Alert. Published May 7, 2024. Accessed August 12, 2024. https://www.sciencealert.com/new-genetic-form-of-alzheimers-identified-in-people-with-common-risk-factor