What Your DNA Test Will Not Tell You
I am talking about the DNA testing kit marketed by 23andMe. Until recently, these kits were used solely to analyze a person’s ancestry. In April, the FDA approved the expanded use of its DNA kit to include information about a person’s health, including genetic predispositions to develop ten different diseases. One of these diseases is Alzheimer’s.
Alzheimer’s and APOE4
If you want to know if you are at risk for Alzheimer’s, 23andMe will test your DNA for the presence of APOE4, a known risk factor for late-onset Alzheimer’s. APOE is a protein associated with clearing fatty substances from tissue. There are three variants: APOE2, APOE3, and APOE4. About 8% of the population have the APOE2 gene, which confers some protection against Alzheimer’s; 78% have the APOE3 variant, which does not seem to influence development of Alzheimer’s. The remaining 14% have the APOE4 variant. Clinical trials have determined that about 40% of those diagnosed with Alzheimer’s have the APOE4 variant. Therefore, if you have APOE4, you have an increased risk for developing late-onset Alzheimer’. Before you send some saliva off to see if you are at risk for Alzheimer’s, consider this information:
- APOE4 is a Risk Factor, Not a Diagnosis
Not everyone who has the APOE4 gene will develop Alzheimer’s. Not everyone with Alzheimer’s has the APOE4 variant.
- APOE4 Is Not the Only Gene Associated with an Elevated Risk of Alzheimer’s
The APOE4 gene is a known risk, but it accounts for less than half the cases of late onset Alzheimer’s. Researchers have now identified 100 other genes that are likely to impact one’s predisposition for this disease. Thus, you may not have APOE4, but you may still have an elevated risk of the disease.
- There are no treatments yet for Alzheimer’s
At the present time, there is no cure for Alzheimer’s, and no treatment that slows or stops the progression of this disease. Therefore, even if you know you are at risk, there is no medication that you can start to reduce your risk.
- Will Your DNA Information Be Secure?
It is so tempting to find out if you are predisposed for Alzheimer’s. What a relief it would be to know that you were not at risk. Unfortunately, these DNA tests don’t provide that level of information, although people may misinterpret results, thinking they are receiving definitive information.
Commentators have been critical of allowing genetic testing to be given to consumers without the counsel of medical professionals who can put the information into context. There is a legitimate concern that those who are told they don’t have APOE4 will think that they are not at risk for Alzheimer’s, and that those who are told that they have APOE4 will live burdened with the impression that they are destined to develop this disease.
The fact is that this test will only tell you if you have one out of 100 risk factors. It cannot tell you how strong your risk is, or when symptoms will appear. Even if the test discloses that you are at risk, that knowledge does not lead to any treatment to offset the risk. Before you part with your $199, make sure you understand what you are, and are not, going to receive.