Direct-to-consumer DNA testing


Professor Ron Trent

4 September 2008

How reliable are direct-to-consumer DNA tests? What do the test results really mean and do we need help interpreting them?

Chair of the NHMRC Human Genetics Advisory Committee, Professor Ron Trent, warns Marilyn Chalkley that claims for ‘lifestyle’ DNA tests – such as what skin creams, foods or health supplements match your genetic profile – should be carefully checked. When it comes to serious health issues, he says, your test results are not only complex but also relevant to other members of your family. And even your doctor may need help from a professional genetic counsellor to interpret the results before being able to explain them to you. So trying to interpret direct-to-consumer DNA test results yourself could be fraught with problems.

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Transcript of podcast

Voice-over: Welcome to this National Health and Medical Research Council podcast. Our Podcasts aim to keep you in touch with major health and medical research issues and the people who shape them.

Introduction: Hello I’m Marilyn Chalkley. Genetic testing is a billion dollar industry world wide and increasingly companies are offering DNA tests on-line. All you have to do is post off a swab from the inside of your cheek, pay a large sum and ask for the genetic test of your choice.

Are your children likely to become diabetic?

Will they become good at sport?

Or do you have the genetic predisposition to develop breast cancer?

All these tests are offered on-line. To find out more I’m talking to Professor Ron Trent of Sydney University, Chair of the NHMRC Human Genetics Advisory Committee.

Welcome Ron.

Prof. Trent: Good afternoon Marilyn.

Interviewer: How easy is it to do a genetic test on-line these days?

Prof. Trent: Well it’s fairly easy actually because the advertising is there, lots of information is provided in terms of what sort of tests you can do, and all you really need to do technically is take a mouth swab or perhaps a sample of blood and put it in the mail and off it goes to a laboratory and back comes a result a couple of weeks later.

Interviewer: And do you know how to interpret that result?

Prof. Trent: Well it really will vary. For some genetic tests the result is straight forward, it’s a yes or no answer so that’s not a big issue but for all of the complex or more important genetic diseases the result could be quite difficult to interpret and this sometimes requires more than one visit to the doctor to see what the test means, it may require additional information coming from a genetic counsellor and so in those situations the direct-to-consumer testing puts the person at quite a disadvantage.

Interviewer: Because in fact they’ve gone and ordered a test on-line, they haven’t gone to their doctor, they’ve just sent off a swab, they’ve got a result back and then who do they talk to if they don’t understand what’s happening?

Prof. Trent: Exactly right, so when you look at the reports and the reports are written in different ways. A report may say you have a risk of a particular condition. Well what does risk mean, is it 100 per cent is it 90 per cent is it 10 per cent, these are some of the issues that you really need to discuss with someone whose used to the tests, what they mean and this is not available in direct-to- consumer testing.

Interviewer: Now of course you do genetic DNA tests don’t you at Sydney University?

Prof. Trent: That’s correct.

Interviewer: But you do it for doctors. What are some of the issues that come up as a result of a DNA test?

Prof. Trent: Well there are lots of issues. Some of the doctors that order the tests actually need help in terms of what can this test offer my particular patient, what does the mutation mean, what does the change mean to my patient’s health, is this 100 per cent accurate this test, are there any problems with the test methods? For example PCR is the usual technology used to do these tests, PCR is very powerful, a great technology, but it makes mistakes and it’s important for people when they have a test that they appreciate what are the limitations of my genetic test.

So some of these discussions are to and fro discussions with the doctor ordering the test or the genetic counsellor so both the doctor, the patient, the family are all aware of the limitations.

Interviewer: But if you order an on-line test you might well be ordering it from overseas.

Prof. Trent: Yes you can order them overseas or locally but if you order them from an overseas laboratory you have the additional problem in many ways of not knowing much about the laboratory, so in Australia we have very specific accreditation conditions. We’re actually not too sure what the accreditation conditions are for some of these direct-to-consumer testing laboratories overseas.

Interviewer: And also how reliable are the DNA tests that you do order from overseas, how do you know whether they’re a good test or not, how do you know if they’ve looked at the right genes?

Prof. Trent: That’s a good question. Some of the claims let’s say for diabetes as an example, type 2 diabetes, is that by doing a DNA test a direct-to-consumer testing laboratory can provide you information about your risk for development of diabetes. Now we know when we look at the research in diabetes that there are many, many genes — maybe 20 or more genes that are associated, none of these genes in themselves cause diabetes they just contribute towards the development. The environment and what we eat and all the other conditions that may contribute to diabetes are also important components and so to put a single direct-to-consumer test into perspective it must be very difficult to come up with real risk factors just from a couple of DNA tests, a couple of genes that might be tested for.

Interviewer: But genetic testing on-line is really taking off isn’t it, because it’s not only health that people can find out about they can apparently find out about all other sorts of almost life well-being sort of issues?

Prof. Trent: That’s true. If you look at the ‘Essentially Yours Report’ that came out in 2003 — this was a combined activity of the Australian Law Reform Commission and the National Health and Medical Research Council, in the ‘Essentially Yours Report’ it identified the issue of direct-to-consumer testing but at that time it wasn’t happening, it wasn’t really a major issue. Today in the US for example we’ve got over 35 companies now that are offering this directly to consumers and the number of companies that are involved becomes bigger every day as more and more genes are identified. So it really is quite a large industry and there’s a lot of money involved in this and so it’s really now become an issue that needs to be considered and addressed in terms of health tests and you mentioned also that there are a range of other life style tests. Some of these purport to give you information from your genes as to what sort of creams you should put on your skin to ensure that it’s the best skin possible or some of the companies that are called Nutrigenetic companies claim that by looking at your DNA profile they could make recommendations about what sort of food you should eat or what sort of particular ingredients the company could give you that might make a difference in terms of your life quality. These are the sort of claims that need to be looked into quite seriously because while life-style issues are not medical issues they may have an impact in terms of your health.

Interviewer: So what would you think about those sorts of tests?

Prof. Trent: Well I think the lifestyle tests are choice tests so if anyone really has a choice to have a test if they want to it’s important that they appreciate that there are claims made and people should look carefully at these claims, but I think that’s just a fact of life and this happens in lots of areas of life. When these tests start to impact on health issues that’s when the alarm bells ring because then the important thing to appreciate about a genetic test is any information that is provided about you has relevance to members of your family, so if you have a genetic test which implies that you’re at risk then other members of your family are also at risk. On the other hand if the genetic test says you’re not at risk then your family members are also not at risk. So whatever information comes from a genetic test has important implications for the person and the family, so therefore these direct-to-consumer tests have to be done appropriately. There may be a role for some direct-to-consumer tests but they have to be carefully done, in the right circumstances and there has to be support provided if it’s needed in terms of what the results mean.

Interviewer: Thank you very much it’s been most interesting. Professor Ron Trent of Sydney University who’s Chair of the NHMRC Human Genetics Advisory Committee talking about direct-to-consumer DNA testing.

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