Genetic testing is now available to consumers to satisfy a variety of desires—tracing heritage, gauging risk of inherited diseases in children, and screening for disease. However, risks come with what doctors say is incomplete knowledge. Experts discuss uses, risks, and future of consumer genetic testing.
- Dr. David Balding, Professor of Statistical Genetics, University of Melbourne and University College, London
- Dr. Wayne Grody, Professor of Pediatrics, UCLA School of Medicine
- Dr. Steven Monroe Lipkin, Professor of Medicine, Weill Cornell College of Medicine and author, The Age of Genomes
- Dr. Gerald Feldman, Professor of Pediatrics, Pathology and Molecular Genetics in Medicine, Wayne State University School of Medicine and President, American College of Medical Genetics and Genomics
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16-42 direct to consumer genetic testing
Reed Pence: Genealogy is a great pastime for many people, and in recent years, websites devoted to genealogy have become extremely popular. So has one particular feature that many of these websites offer–the opportunity to get a DNA profile of your ancestral heritage just by spitting into a cup. But what exactly can these direct-to-consumer genetic tests tell you?
David Balding: The truth is we’re all a bit of a mish-mash, so these tests can tell you some things that are somewhat interesting but most of the companies overstate the reality about what the test can really tell you.
Pence: That’s David Balding, professor of statistical genetics at the university of Melbourne in Australia and at University College in London.
Balding: All these tests do is they’ve got some database of people who say where they come from and then when a new customer comes along they check any kind of partial matches of bits of the DNA that match up with somebody and then they say, okay if that person said they were Hungarian and you have a near match with them then they say, “Okay, you’ve got some ancestor who was Hungarian.” Well maybe, that’s a reasonable guess, but it’s not very accurate. It depends on a lot of things – who they happen to have in their database and whether they accurately describe where they come from and also national boundaries don’t necessarily reflect the real differences between groups.
Pence: That’s not really saying much, given how much information is in our genome… if we knew how to get it.
Balding: DNA is a very, very long sequence of chemical bases and it’s about three billion letters long. If you think about each of them being a letter A, C, G or T there’s about three billion of those. Most of them were all the same, so it’s not really, being able to actually read all the letters in the genome is now possible, but it’s still quite expensive and so they won’t be doing that. Instead of reading all three billion they just pick out certain places in the genome where there tends to be differences between individuals and so the most informative sites. And it’s really just a question of, you know, how much money you want to pay and the latest because the technology keeps changing all the time with new genotyping chips come out. The first generation had about 300,000 markers. They’re up towards a million now as being typical. That’s still only a small fraction of the whole genome, but it’s still a lot of information.
Pence: Balding says you can think of the human genome as being similar to the human skeleton. Barring any deformity, all of us have the same number of bones… and the kneecap, for example, is in the same location person to person. The bones themselves, though–the exact size and shape of them–differ. The genome is similar. The genes, or markers for ethnicity, for example, are found in the same area in every genome. But ancestry isn’t the only area where consumer interest in genetic testing has skyrocketed. Dr. Wayne Grody is a professor at the UCLA School of Medicine in the Department of Pediatrics and Clinical Laboratory. He points to the growing popularity of what are called expanded carrier screening tests.
Dr. Wayne Grody: This is for couples who are usually pregnant or sometimes planning a pregnancy to see if one or both of them carry a mutation in a gene that would present a risk of having a baby affected with that disorder.
Pence: Grody says today it’s standard practice for couples to be screened for a handful of disorders within certain ethnic and racial groups, such as cystic fibrosis, sickle cell anemia and Tay-Sachs disease. However, the expanded carrier screen tests for up to 110 possible disorders. Grody takes issue with these tests because we all carry three or four hundred gene variants that could possibly cause a disorder. It’s just that they rarely do.
Grody: A cynical person would say, “Well, it’s just marketing.” To a naïve patient or provider a hundred diseases for the same price or less as doing 10 diseases, wow, that sounds like a good deal. But if you dig down a little deeper, you may find that many of the things tested for are incredibly rare, so it’s hardly worth doing it on everybody. Or, if you do find it, it may be a mild disorder that most couples would not consider terminating a pregnancy for. And some are even not symptomatic at all in the majority of patients.
Pence: Still, some people might say being forewarned is being forearmed.
Grody: Some people make the case that, oh, we have no intention of terminating. We just want to know so we’ll be prepared. There are some disorders where that would be useful information, where you really need to begin treatment on Day One of life. Most of the disorders in their panel are not like that or, if they are, they are disorders that are already screened in the newborn screening programs that are in all 50 states so they would be diagnosed on Day One anyway. I’m not hugely persuaded by the reason to do it simply to know ahead of time.
Pence: Plus, Grody says there’s also a downside to knowing. He fears that knowledge of unpredictable outcomes will cause parents undue anxiety.
Grody: I’ve also seen instances where there’ve been DNA changes like these novel variants that I can’t really predict what they would do in the baby, so parents agonize over those. In most cases they’ve chosen not to act on it, which I think is the proper thing to do. But then they’re worried for the rest of the pregnancy and even when the child is born they’re kind of on edge waiting for some symptom to appear which may never appear.
Pence: There’s also growing consumer demand for genetic tests to inform your own medical care. Medical geneticist Dr. Steven Monroe Lipkin is a professor at the Weill Cornell College of Medicine in New York and author of The Age of Genomes. He calls consumers of those tests the worried well and includes himself in that category.
Dr. Steven Monroe Lipkin: The fact that more people are interested and recognize that genetics has a lot of potential information to offer for people to be able, one, to work on disease prevention and to keep them sort of healthier longer; two is for people are, you know, understanding that, thinking “Hey. My family has on my mom’s side, you know we have some interesting medical issues that come up.”
Pence: Lipkin is concerned that there’s no federal regulation of these tests, so genetic testing labs don’t have to meet specific quality control measures other than the Basic Clinical Laboratory Improvement Amendments, or CLIA, established in 1988.
Lipkin: So this has enabled a bunch of companies to come up that present genetic tests that may not have a whole lot of evidence really backing them up. Unfortunately, I think some companies have kind of tried to sneak in there a little bit to be able to provide really “not ready for primetime” tests. For example, you can think about, you know if you want to know, you know, “What is my chance of having a heart attack?” you want to get a number that’s based on really firm data and not one that’s based on, you know, relatively few inputs to a model that may not have been adequately tested. One of the things I think has to happen is for the FDA to step in and to take on more of a role, actually, in regulating genetic tests to consumers as well as medical testing.
Pence: Lipkin says the FDA has proposed greater regulation in the genetic testing industry.
Lipkin: There’s been a bit of a pushback, actually, from some lobbying organizations including organizations of laboratories, actually. So at the moment it’s sort of unclear, really, how the quality control will work out in the near future.
Pence: Case in point? Lipkin spent $2,500 to get his complete genome mapped, but the results were incorrect.
Lipkin: They were kind of data that hadn’t been adequately analyzed and told me that I actually had a rare disease called Coffin-Siris Syndrome which I knew I didn’t have because I didn’t have any of the symptoms and I have two healthy daughters and neither of them had any of the symptoms. So that actually made me go back and want to have it redone, to spend more money to have it done in a more comprehensive and quality-intensive way.
Pence: So Lipkin had his genome sequenced a second time by a different lab, this time at a cost of $5,000.
Lipkin: For people who are interested in genetic testing for having very strong personal or family medical history, the first step is to talk to their physician or get referred to a genetic counselor who are health professionals who, in fact, are experts in knowing which are the best genetic tests to perform for different diseases. And they can help you to navigate through the long list of potential companies.
Dr. Gerald Feldman: There are many reasons why some consumers would prefer to order the tests directly. They may want to know information without including their healthcare professional in that test. They may feel that they have an adequate understanding of the test itself and therefore feel that it’s within their right to order a medical test. They may want to keep the information private to themselves, or they may want to know particular family information from ordering a test. So there are many reasons why one might consider ordering a test without a professional.
Pence: That’s Dr. Gerald Feldman, professor of pediatrics, pathology and molecular genetics in medicine at the Wayne State University School of Medicine and president of the American College of Medical Genetics and Genomics. He says that while privacy is one reason for people to order testing without their doctor, there’s one other way you need to look at that issue. Your doctor may not know… but what does the testing company do with your genetic information once they have it?
Feldman: The patient truly needs to understand what information they’re going to be getting and they need to know exactly what privacy concerns are being addressed in this particular test that they might have. So first they need to be informed beforehand of who’s going to have access to these test results, what processes are in place to protect these results, what happens to the DNA sample once the test has been completed, will it be sold to third parties? So all of that kind of information I think is very important for the consumer to think about and make sure that they understand the answers to those questions before they provide a sample for such testing.
Pence: For example, Feldman says many companies are interested in tracking genetic changes in the general population. By acquiring genetic test results from a large demographic, pharmaceutical companies can get a head start developing new drugs to treat certain genetic changes or diseases. So, how easy is it for someone to order a genetic test?
Feldman: Various companies offer different types of direct-to-consumer testing with different levels of healthcare involvement. Some allow one to begin the testing process online, but require a physician approval before sending in the actual test. Others will accept a sample directly from the patient and that has evolved over time. Some companies that used to do that don’t offer that anymore. And then some offer the opportunity for one to speak with a board-certified geneticist or genetic counselor but don’t necessarily require that.
Pence: Whether you rub your hands with glee at finding out your ancestry, or wring your hands with worry, one thing is certain – the genetic testing industry will only continue to grow. Already the global market is growing at an annual rate of nearly 10 percent and experts expect the DNA test market to be worth more than $10 billion by 2022. You can learn more about all of our guests and about Lipkin’s book The Age of the Genome by visiting our web site at RadioHealthJournal.net. Our writer/producer this week is Polly Hansen. I’m Reed Pence.