The Alzheimer’s gene: to test or not to test, that is the question
Here’s an article about a woman whose mother died of Alzheimer’s, and who decided to get tested for the Alzheimer’s genetic marker in hopes it might reassure her, and discovered she actually has a double dose of the gene that predisposes people to Alzheimer’s. That news has thrown her into even more worry, although she has been doing more traveling to places on her “bucket list.”
I decided quite some time ago not to do genetic testing to see if I have genes for any diseases. I’m pretty sure I do, and I’m pretty sure I know what some of them are, and I already try (but sometimes fail) to live my life in ways that might prevent those diseases or at least stave them off longer. If there was a very effective early treatment for something, maybe I’d do the testing. But right now, no.
Alzheimer’s is one of those diseases about which we know quite a bit but not nearly enough. For example, even the genetic marker doubly possessed by the woman in the article – which reportedly makes her chances of getting Alzheimer’s eight to twelve times more likely than those with a neutral version of the gene (notice, by the way, that the figures are expressed in the difficult-to-interpret form of relative risk rather than absolute risk) – doesn’t make the disease a sure thing for her. It turns out that having the more dangerous gene does not mean that a person will get Alzheimer’s, and not having it doesn’t mean that a person won’t get it. It’s far more complicated, as the article I just linked explains.
For example:
But not everyone who has one or even two APOE e4 genes develops Alzheimer’s disease. And the disease occurs in many people who don’t even have an APOE e4 gene, suggesting that the APOE e4 gene affects risk but is not a cause. Other genetic and environmental factors likely are involved in the development of Alzheimer’s disease.
The article goes on to list seven more genes that seem to affect Alzheimer’s, and it’s not at all certain that’s all there are. So the conclusion is:
Most experts don’t recommend genetic testing for late-onset Alzheimer’s. In some instances of early-onset Alzheimer’s, however, genetic testing may be appropriate.
Most clinicians discourage testing for the APOE genotype because the results are difficult to interpret. And doctors can generally diagnose Alzheimer’s disease without the use of genetic testing.
As the saying goes, old age is not for sissies.
A former student of mine, now in her early 50s, tested high for breast cancer. She opted for a double mastectomy. I thought it a bit extreme, but it removes all concern for her.
physicsguy:
People with a family history of early breast or uterine or pancreatic cancer should be tested for that gene, because there is preventative treatment, and early knowledge and detection makes a difference. I exempt those cases from what I’m discussing in this post, which are illnesses like Alzheimer’s which don’t have those characteristics
A relative’s mother and grandmother both died of ovarian cancer. Once our cousin had given birth to her family, she had the ovaries and uterus out. Her chances of getting the cancer were very high, and cure rates are very low.
But for something like Alzheimer’s, other than avoiding obesity and blood sugar problems and staying mentally and physically active, there are no preventives and no effective treatments. And you should do the healthy living things for a lot of other reasons. Why frighten yourself with testing which yields no useful approaches but only fear?
Neo said “People with a family history of early breast or uterine or pancreatic cancer should be tested for that gene, because there is preventative treatment, and early knowledge and detection makes a difference.”
Can you direct me to a link or something about the preventive treatments you referred to? I goggled around and could only find the bland lifestyle advice … ??? Very interested in any additional info.
Nobody Important:
One preventative treatment I’m talking about is pretty drastic: surgery. That is, removal of breasts, and then reconstruction, and/or removal of ovaries (usually after menopause), as well as more stringent and frequent screening. Sometimes, also (or instead), the person can take certain selective hormone blockers. This website discusses the options.
Thank you!
Chris Hemsworth is pulling back from acting after he discovered he was a carrier.
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Neo, you mentioned pancreatic cancer. Do they remove the pancreas as a preventive measure?
From conception a la Downs syndrome, perhaps the female sex in one Choice. Abort.
Kate:
No, but the way it works is this: the same gene predisposes to breast, ovarian, and/or pancreatic cancer. So if any of those run in your family in people who aren’t quite old, you probably need to be screened for the gene. Then if you test positive, you have to decide what to do, because you have an increased risk of any or all of those cancers. For breast and ovarian there are the surgical options, the drug options, and the more-screening option (not mutually exclusive). For pancreatic I assume the only option is increased screening. But my understanding is that anyone with the gene can get any of them, and therefore has to be aware of all of them. I think there are also different variants of the gene, and they carry different levels of risk.