Research indicates that the presence of two copies of the APOE4 gene may be responsible for up to 20% of Alzheimer’s cases.

Alzheimer’s disease (AD) is a complex neurodegenerative disorder that affects millions of people worldwide. While the exact causes of AD are not fully understood, researchers have long known that genetics play a significant role in the development of the disease. In a recent study published in Nature Medicine, a team of neurologists from Spain and the U.S. have made a groundbreaking discovery that sheds new light on the genetic underpinnings of AD.

The researchers found evidence suggesting that up to 20% of all cases of Alzheimer’s disease may be attributable to having double copies of the APOE4 gene. Previous research has established that homozygous APOE4 genes (meaning having two copies of the gene) are a significant risk factor for the genetic form of AD. However, this new study suggests that AD caused by homozygous APOE4 genes should be classified as a distinct type of the disease, rather than just a risk factor.

The team analyzed data from thousands of deceased AD patients as well as biomarkers in an additional 10,000 living patients to arrive at their findings. They discovered that individuals with homozygous APOE4 genes exhibited high levels of amyloid in their brain fluid by the age of 65, indicating full penetrance of the disease in these patients. Moreover, the age at which symptoms appeared and the evolution of biomarkers in individuals with homozygous APOE4 genes followed predictable patterns, further supporting the classification of this subtype of AD.

The researchers propose that between 15% and 20% of AD cases may be linked to homozygous APOE4 genes, underscoring the importance of considering this genetic factor as a unique form of the disease. Their findings point to the need for targeted therapies and interventions tailored specifically for individuals with this genetic predisposition.

This study represents a significant step forward in our understanding of the genetic basis of Alzheimer’s disease. By identifying homozygous APOE4 genes as a distinct genetic form of AD, researchers can now explore new avenues for personalized treatments and potentially improve outcomes for a subset of patients. As further research on this topic continues, the potential impact on the field of neurology and the development of therapies for AD is promising.

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