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Posts Tagged genetic testing

And Now for Something Completely Different

This will be a departure from my usual posts. Several announcements in the news and medical journals have caught my attention recently, and as I delved into the details, I thought I would share them with our SBM readers. Topics include AIDS cures, the continuing danger of polio, eating nuts for longevity, racial differences in vitamin D, and the use of pharmacogenetic testing to guide the dosage of anticoagulant drugs. They are all examples of science-based medicine in action.

Have patients been cured of AIDS?

I read that the HIV virus had returned in patients thought to have been cured by bone marrow transplants, and I mistakenly thought they were referring to the original claim of cure I had read about. Nope, that one still stands. (more…)

Posted in: Clinical Trials, Nutrition, Pharmaceuticals, Vaccines

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Meet Your Microbes: uBiome Offers New Service

We are not alone. Walt Whitman didn’t know how right he was when he said, “I contain multitudes.” The microbes on and in our bodies outnumber our own cells 10:1.  Perhaps that creeps you out. Perhaps that makes you curious to know just who all these billions of creatures are that are using your body for a home and a transportation device.

For just $89 you can learn what’s in your gut, nose, mouth, skin, genitals…or sample anything!

The offer comes from uBiome, a “citizen science startup” that has scientific goals somewhere down the line, but for the moment is happy to just provide a personal service, to sequence your microbiome and tell you how you compare to others. The current utility of this offering is questionable. It’s just not ready for prime time. (more…)

Posted in: Diagnostic tests & procedures, Medical Ethics

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Angelina Jolie, radical strategies for cancer prevention, and genetics denialism

I had been debating whether to blog about Angelina Jolie’s announcement last week in a New York Times editorial entitled My Medical Choice that she had undergone bilateral prophylactic mastectomy because she had been discovered to have a mutation in the BRCA1 gene that is associated with a very high risk of breast cancer. On the one hand, it is my area of expertise and was a big news story. On the other hand, it’s been nearly a week since she announced her decision, and the news story is no longer as topical as it was. Also, I’ve already written about it a couple of times on my not-so-super-secret other blog, making the division of blogging…problematic. So, if some of this is a bit repetitive to those who are also fans of my more—shall we say?—insolent persona, I apologize, but try to be patient. I will be doing more than just rehashing a couple of posts from last week (although there will unavoidably be at least a little of that), because there have been even more examples of reactions to Jolie’s announcement that provide what I like to consider “teachable moments.” I will start by asserting quite bluntly that in my medical opinion, from the information I have available, Angelina Jolie made a rational, science-based decision. How she went about the actual mechanics might have had some less than scientific glitches along the way (more about that later), but the basic decision to remove both of her breasts to prevent breast cancer associated with a BRCA1 mutation that she carried was quite reasonable and very defensible from a scientific standpoint.

One advantage of waiting nearly a week to write about this story is that it provided me with the opportunity to sit back and observe the reactions that Jolie’s decision provoked. One thing that I really didn’t expect (although in retrospect maybe I should have) is the pure denialism on display that genes have any effect whatsoever on cancer. I say “in retrospect I should have” because I’ve written at least a couple of times before about how quacks use and abuse the term “epigenetics” in the same way that they abuse the word “quantum” and how they seem to believe that wishing makes it so (through epigenetics, of course!) to the point where they believe that genetics is irrelevant to cancer. Indeed, they go far beyond that, asserting that, in essence, environment is all. From what I’ve been reading thus far, the second strongest strain of reaction to Jolie’s announcement (after revulsion at the “mutilation” of women that it represented to certain quacks) is pure denial that mutations in BRCA1 and BRCA2 genes portend such a high risk of ultimately developing breast cancer. This denial is often accompanied by conspiracy mongering about BRCA1 and BRCA2 mutations being a “conspiracy” on the part of the “cancer industry” and Myriad Genetics & Laboratories, the company that holds the patents on BRCA1 and BRCA2, to increase genetic testing and preventative mastectomies. Myriad happens to have a complete monopoly on BRCA1 and BRCA2 testing because of this patent and has been criticized for its high prices and stifling of competition. There is currently a case before the U.S. Supreme Court regarding whether human genes are patentable under the law. I’m not a big fan of Myriad, and I’ll tell you why later. (Not that it matters; I’m stuck with them for now.) My personal distaste for Myriad Genetics aside, this sort of conspiracy mongering is part and parcel of the quack approach to denying the significance of BRCA1 mutations.

This denial is usually coupled with confident blather that Angelina Jolie didn’t need to undergo “disfiguring” surgery to prevent BRCA1-associated breast cancer but instead could have achieved the same—or even better!—risk reduction if only she had used this magic herb or that miracle supplement and making certain “lifestyle” changes. It’s utter nonsense, of course, but it’s everywhere.

Before I get to the reactions to Jolie’s announcement, let’s first take a look at what she did, why, and the science behind it.
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Posted in: Basic Science, Cancer, Medical Ethics, Science and the Media

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Direct-to-Consumer Genetic Testing: Road Map or Tarot Cards?

A topic of growing interest (and concern) at SBM is laboratory and diagnostic test pseudoscience. Bogus tests are everywhere, and Kimball Atwood recently discussed several of them. But over the past several years, diagnostic tests have emerged that appear to be science-based and offer gene-level insights into your health. And these tests don’t even require a physician’s visit – just a swab of saliva and a credit card get you reams of information on your genetics, traits, and risks of dozens of diseases. It looks like the ultimate in consumer health information, with the potential to offer truly personalized treatment strategies. Companies like 23andme, deCODEme, and Navigenics all promise “genetic insights” to improve your health. How could this information be anything but helpful?

Personalized medicine describes medical practices that use information about a person’s genes, proteins, and environment to prevent, diagnose and treat disease. Science-based practice has routinely incorporated environmental advice (e.g., diet and exercise) into medical management. And there are a number of genetic tests in routine use that are well established, clinical validated, and are highly predictive of future outcomes, such as tests for Huntington’s disease and hereditary breast cancer.
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Posted in: Diagnostic tests & procedures

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Genetic Testing for Patients on Coumadin

Anticoagulation is advised for patients who have had a blood clot or who are at increased risk of blood clots because of atrial fibrillation, artificial heart valves, or other conditions. Over 30 million prescriptions are written every year in the US for the anticoagulant warfarin, best known under the brand name Coumadin. Originally developed as a rat poison, warfarin has proved very effective in preventing blood clots and saving lives; but too much anticoagulation leads to the opposite problem: bleeding. A high level of Coumadin might prevent a stroke from a blood clot only to cause a stroke from an intracranial bleed. The effect varies from person to person and from day to day depending on things like the amount of vitamin K in the diet and interactions with other medications. It requires careful monitoring with blood tests, and it is tricky because there is a delay between changing the dose and seeing the results.

In his book The Language of Life, Francis Collins predicts that Coumadin will be the first drug for which the so-called Dx-Rx paradigm — a genetic test (Dx) followed by a prescription (Rx) — will enter mainstream medical practice. FDA economists have estimated that by formally integrating genetic testing into routine warfarin therapy, the US alone would avoid 85,000 serious bleeding events and 17,000 strokes annually.
A recent news release from the American College of Cardiology described a paper at their annual meeting reporting a study of

896 people who, shortly after beginning warfarin therapy, gave a blood sample or cheek swab that was analyzed for expression of two genes — CYP2C9 and VKORC1 — that revealed sensitivity to warfarin. People with high sensitivity were put on a reduced dose of warfarin and had frequent blood tests. People with low sensitivity were given a higher dose of warfarin.

During the first six months that they took warfarin, those who underwent genetic testing were 31 percent less likely to be hospitalized for any reason and 29 percent less likely to be hospitalized for bleeding or thromboembolism than were a group that did not have genetic testing.

Epstein said that the cost of the genetic testing — $250 to $400 — would be justified by reduced hospitalization costs.

At this point, I don’t believe this study. I’ll explain why I’m skeptical. (more…)

Posted in: Clinical Trials, Pharmaceuticals

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