APOE Gene Variant Linked to Alzheimer's Risk, But Many Without It Still Show Signs of the Disease
A recent study presented at the 2025 National Society of Genetic Counselors (NSGC) Annual Conference reveals a fascinating yet complex story about Alzheimer's disease risk. While the APOE ϵ4/ϵ4 gene variant is a strong predictor of higher Alzheimer's risk, the study shows that many individuals without this allele still exhibit true Alzheimer's disease (AD) pathology.
The Power of APOE ϵ4/ϵ4 in Predicting Alzheimer's:
The study analyzed biomarker testing data and found that individuals carrying the APOE ϵ4/ϵ4 variant were significantly more likely to have biomarkers indicating mild cognitive impairment or AD-associated dementia. This discovery reinforces the well-known association between APOE ϵ4 and Alzheimer's risk.
But here's where it gets intriguing: The Complexity of Biomarker Interpretation
Despite the strong link with APOE ϵ4/ϵ4, the study also found a substantial number of individuals without this gene variant showing biomarker evidence of AD. This finding highlights the intricate nature of interpreting biomarker results and the potential for false negatives or positives.
The study, led by Matt Tschirgi, MS, CGC, examined data from 21,267 individuals who underwent beta-amyloid testing, with 27.1% classified as higher risk, similar to previous research. Interestingly, no significant differences were found between individuals homozygous for APOE ε3 and APOE ε4.
Unraveling the Genetic Puzzle of Alzheimer's
Researchers delved into the genetic aspects by performing APOE genotyping on blood samples. Among those who underwent p-tau 181 testing, nearly half showed results consistent with mild cognitive impairment or AD-related dementia. The APOE ε4 homozygotes had significantly higher biomarker results for MCI or dementia compared to non-carriers.
However, when it came to p-tau 217 testing, the results were less clear-cut. Around 56% of individuals had results consistent with MCI or dementia due to AD, with no significant difference between APOE ε3 and APOE ε4 homozygotes.
The Role of Genetic Counselors in Navigating Complexity:
The study emphasizes the importance of certified genetic counselors in interpreting complex biomarker and genetic results. As new AD therapies emerge, counselors may play a crucial role in helping individuals understand discordant or ambiguous results, enabling informed decision-making.
With the growing focus on AD due to advancements in therapies and biomarker testing, discussions about the role of genetic counselors in testing practices are gaining momentum. The authors note that while APOE testing has been available for years, newer blood biomarker assays may introduce additional complexities to counseling discussions.
And this is the part most people miss: The Ongoing Debate in Genetic Counseling
The study's findings spark an interesting debate: How should genetic counselors navigate the complexities of AD risk assessment, especially when biomarker results don't align with genetic predictions? As AD research progresses, the role of genetic counselors in providing clarity and guidance becomes increasingly vital.
What are your thoughts on the role of genetic counselors in interpreting complex biomarker and genetic results? Do you think their involvement is crucial for informed decision-making in Alzheimer's disease management? Share your opinions in the comments below, and let's continue this fascinating discussion.
