forum discussion #16

The Benefits and Burdens of Genetic Testing

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Listen to a story by reporter Marina Giovannelli, followed by our interview with Mayana Zatz.
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Our guest in the Science Forum is geneticist and genetic counselor Mayana Zatz. She directs the Human Genome Research Center at the University of Sao Paolo.

Zatz has been working with patients with inherited disorders for nearly two decades. When it comes to genetic testing, Zatz advocates caution. Tests for some inherited disorders have helped people decide whether or not to have children. But in most cases, Zatz says genetic testing raises complex psychological and ethical issues.
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  • Should children be tested for late-onset disorders like Huntington’s disease and cerebellar ataxia? Doing so could lead to a life of dread, as they wait for a disease for which there is no cure.
  • Interpreting the results from a genetic test can be difficult, especially for complex diseases like cancer or Alzheimer’s which are triggered by multiple factors, not just genetics.

Come join the conversation with Mayana Zatz. She’s taking your comments and questions through July 13th.

  • Have you had your genes read? How did the results change your life?
  • Should companies offering such tests be regulated?
  • What kinds of medical benefits can we expect from genomics research in the coming years?

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Your Comments

  1. Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

    Hi, and welcome to the discussion on genetic testing. Such tests can be useful to people with inherited genetic disorders. But, what about getting our genomes sequenced? Is that a good idea? Would you get your genes read to learn more about your health risks? Or would you rather leave your genes alone and lead a healthy lifestyle anyway? I look forward to hearing from you.

  2. I admire and respect the work of Dr. Nancy Wexler – one of my personal heroes. For me, genetic testing has been very beneficial. The HD test was not available until I had all 3 of my children, who inherited it from their father. Their father passed away in 1989, and my youngest daughter died 7 months ago. I realize that education and and family resources are critical for patients with a fatal disease. I continue to advocate for education of Huntington’s Disease and to partner with organizations that provide family resources and counseling, as well as encouraging individuals “at risk” who wish to have a family to consider in vitro fertilization and pre-implantation diagnosis that would end HD in their own family line.

    • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

      Hi Frances

      Thanks a lot for your comment. I absolutely agree with you. Pre-implantation diagnosis, although technically more difficult has the advantage to allow at-risk couples to have embryos without the mutation implanted even if they do not want to know their carrier status. However, what is your opinion about testing asymptomatic children for late onset conditions such as HD or others for which there is no available treatment?

  3. Beatrice

    As a person in a Huntington’s Disease family who has not been tested and am wondering whether I should- but my brother has kids in their teens and his wife talks about getting the kids tested. I say “no, the kids should not be tested.” They are 11 and 16 years old. At least I had my teens and my early 20s when I could enjoy myself and not worry about this disease.
    My father lived until at least 55 years old until he showed any signs, why deprive someone of all those great years? Even as someone at risk who has seen the disease devastate people I love I am glad to have been born. That being said, I am not sure what to do as far as getting tested and having kids myself.

    • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

      Dear Beatrice
      We face very often this dilemma in the families we see in our Center. On one hand you want to have healthy children but on the other hand you are afraid of being tested. You don´t want to know if you have or not inherited the Huntington’s gene. What is possible is to have pre-implantation diagnosis. The geneticists will implant only the embryos who do not carry the mutation and will not tell you if they found or not embryos with the mutation.This will allow to have non-affected kids without disclosing the parent carrier status.

      • Were you aware that the proposed new version of genetic testing guidelines (as now proposed in Europe) will recommend against pre-implantation diagnosis with non-disclosure for Huntington at-risk individuals?

        My opinion is that this is an infringement of basic human rights as is stated in the “Universal Declaration on the Human Genome and Human Rights”, a legal document agreed to by the United Nations which states that it is: “The right of every individual to decide whether or not to be informed of the results of genetic examinations and the resulting consequences should be respected.”

      • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

        Hi, LaVonne.

        I was not aware that the proposed new version of genetic testing guidelines (as now proposed in Europe) will recommend against pre-implantation diagnosis with non-disclosure for Huntington at-risk individuals. Why? What arguments are they using against? This allows people at-risk that do not want to know to have kids free of the disease.

        I agree with your opinion. Is there anyway we can fight agianst this decision?

      • As far as I know this is still in a committee of the European Huntington Network — though there is a link on the home page of the web site, you must have a log in #. I believe it will be presented first to EHDN members in their September meeting in Prague. As far as I can tell there has not been much (if any) involvement from North American Huntington groups.
        I have given some information on the HDDW website: http://hddrugworks.org/index.php?option=com_content&task=view&id=275&Itemid=26

        I believe there is need to bring this out into the open for more discussion. The North American Huntington organizations, genetic counselors and patient groups certainly need to organize and address this issue.

      • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

        Hi, Lavonne.

        I also believe that this is an important issue that should be discussed thoroughly. We had cases of women who had an affected parent and did not want to be tested but wanted to procreate. Two of them wanted to have in vitro fertilization with a donated egg. The possibility to have pre-implantation diagnosis not only is an alternative to this decision but will allow in some cases to determine that the “at risk” mother has not inherited the mutation.

  4. Hello Mayana,

    I was very interested in what you had to say about the problems with the personalized genetic tests from the pharmacy. One of the problems seems to be the inherent lack of counseling provided with the tests. People don’t necessarily know how to interpret the information they get.

    Do you think that we need more regulation around these tests? What kinds of regulations do you think would be helpful?

    • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

      Hello Bennett

      You are absolutely right. The problem is the lack of genetic counseling. Before getting a genetic test a person should know: Why they want to be tested? For what they are being tested? What is the meaning of a positive result? What is the meaning of a negative result? What can be done about it?

      In the pharmacy test, for example, which is still awaiting FDA approval, there were several tests with completely different impact. For the lay people it is very difficult to understand without a proper genetic counseling. For example, the risk of developing Alzheimer (for which there is still no treatment) and the risk of being carrier of the cystic fibrosis gene and having affected siblings. Do people understand the difference?
      I support that we should have more regulation.

      • Hi Mayana,

        Thank you so much for responding! That’s very interesting. So what do you think they should do? What do you think the regulations should be required? Phone counseling? I was picturing a big warning on the test, like they have on cigarettes, saying, “Warning: The information received from this test can be incomplete or misleading.” What do you think?

  5. Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Rhitu Chatterjee

    Hi Mayana,

    Thanks for participating in this discussion. I was wondering about genomics research. Ongoing research on the human genome requires the analysis of a lot of DNA, & volunteers are contributing their DNA to scientists -The Personal Genome Project- who will then share the data with other researchers.

    But this raises issues about privacy (see this story about a panel discussion on the topic at a recent science conference).

    I’d love to know your thoughts on privacy in the era of personal genomes. Do you foresee privacy and discrimination based on DNA becoming a problem? Has Brazil faced this yet – any court cases related to genetic data? If so, what’re your thoughts on protecting people’s privacy and from any possible discrimination related to their genetic data?

    • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

      Hi Rhitu
      That’s a very important discussion.

      First of all, how can we guarantee privacy? There was an interesting story that happened in Brazil some years ago that can illustrate this issue.Wilma a 50-yr old lady was accused of having kidnapped a newborn baby girl 23 yrs ago. Roberta,who had been raised by this lady as her natural daughter declared she did not want to know. However, when talking to the investigators she smoked and they took the leftovers of her cigarette and analyzed her DNA.The analysis proved that she was not the biological daughter of Wilma. I think that her decision “of not wanting to know” was violated. Others defend that discarded DNA does not belong to you anymore. We leave DNA all over.How can we guarantee it will not be used without our consent?

  6. Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

    Another issue is if DNA samples shoud be anonymous (and become a number) or, if you should keep the identification in confidentiality as we do in Brazil, but which allows to find the donnor if needed. Here is another story from our center. We had collected samples of normal controls to study the variability in the gene responsible for myotonic dystrophy. Surprisingly we found a mutation in a young student who had left our lab. It meant she had a high risk of having an affected child. Should we tell her or not? We thought that the information could be useful and we decided to call her back and informed her. She was very grateful, brought her 3 sisters and they were able to prevent the birth of affected children. This was only possible because the samples were not kept anonymous.

  7. Gustavo Macedo

    Hi Mayana,
    I’m just passing by to congratulate you for bringing your interesting view points. Although I’m not familiar in this area, I love The World’s Science podcasts.
    Saudações!

    • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

      Thanks a lot Gustavo. Maybe you have friends who’re interested in the topic of discussion. A big Brazilian hug, Mayana

  8. Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? David Baron

    Mayana — Thanks for participating in this discussion!

    I’m intrigued by the news today that scientists have identified genes that can predict one’s odds of living past age 100: http://news.bbc.co.uk/2/hi/science_and_environment/10475018.stm

    Can you see any benefit to this sort of genetic test? I mean, is there value in testing not only for the likelihood of disease but the opposite — a tendency for good health and exceptional longevity?

    • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

      Hi David
      That´s an interesting issue. For sure everybody would like to know that they will live a long and healthy life. The question is the impact of a negative result, that is, if you don´t carry the “longevity” genes. Do we want to know?
      On the other hand, I am afraid that retirement plans would love to have such information. If you are “at-risk” of being a centenarian they would probably charge you more. I am curious about the opinion of people following this forum.

      Would you like to be tested to know if you carry or not “longevity” genes?

      • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Elsa Youngsteadt

        I don’t have any desire to know… I don’t think it would affect how I live, and I figure that the lifespans of my grandparents and other ancestors are a good enough clue. I’d be more intrigued just to understand the biology of longevity, rather than to predict it for myself or any other individual.

      • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

        About the “longevity genes” I feel like you, Elsa. I do not want to know if I will live a long life or not. On one hand everybody would like to know that they will be healthy till 100 years old but on the other hand there is a great risk that you will postpone everything for tomorrow. Better to live everyday as if it will be the last one..

  9. Miguel Mitne Neto

    Hi Mayana,

    “Personal Genomics” will become available to a big public in just a few years, despite regulations and laws that may arise. People are becoming aware of insurance companies and privacy. However, do you think that, in a short period of time, it is possible to prepare an individual for the huge RESPONSIBILITY of having such information?

    At the moment a geneticist notifies the result of a test, he/she is giving more than information and counseling to the patient, is providing him the responsibility of using this result in a good way. It means that the tested person will have to judge if: (1) he wants to share that information with relatives or not; in case of an affirmative decision, choose (2) when; (3) how; and many other questions.

    How much information is enough?

    • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

      Hi Miguel

      You raised a very important issue: Personal Genomics. For sure, when it will be possible to screen your genome for ~1000 dollars, lots of people will be interested in analyzing their DNA. The problem is that we are going to have a lot of information with very little knowledge. How to distinguish normal variants from “at-risk” genes? Moreover, some mutations may interfere with your reproductive life. When to tell? How to tell? I remember a lady who was found to be a carrier for Duchenne dystrophy.We told her that her female relatives could be at-risk and they could be tested if they wanted. She replied that she would tell her sister but not her cousins because she hated them. The question is: Can we interfere?

      We will need a multidisciplinary team to deal with the genome era.

  10. Chery Cobb

    Hello Mayana,

    I am a 60 year old who approximately 18 months ago was diagnosed with MAC (Mycobacterium Avium Complex). I have since been on a very strict antibiotic regimen. It is my understanding that this is a very unusual infection to manifest itself in someone with a healthy immune system, but all indications are that I am not immunocompromised. I read one article that said that an increased incidence of aging Caucasion women had been succumbing to this infection and that many, when tested, proved to be carriers of CF. I have two daughters, one who has two children and does not plan to have more, but the younger of the two is just starting to think about starting a family. Can you make recommendations about genetic testing for CF under these circumstances? Are there other at-risk factors for carriers of CF?

    • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

      Hello Chery
      I confess that I don´t know if there is an association between MAC and cystic fibrosis (CF). However even if your older daughter does not plan to have more children there is no harm to be tested for the CF gene. If you find out that you carry a mutation in this gene it might be important for the genetic counseling of your youngest daughter as well as for your grandchildren. Interestingly I found out by chance ( we were testing normal controls) that I carry a mutation in the CF gene. When I learned my first concern was to test my children and inform all my relatives.

  11. Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Elsa Youngsteadt

    Hello Mayana,

    I’ve been thinking about the report from Venezuela, where people participated in the Huntington’s research but are unaware of the genetic test. Whose responsibility IS it to make sure that they do know about the test and have access to it? Is it really Nancy Wexler? Is it the government? The doctors at the local clinic?

    Second, I wonder if the fact that those families participated in the research really means they have a greater right to a genetic test than any other population that is also prone to genetic disease. Their lack of access wouldn’t be as attention-getting had they not participated in the research–but would it really be any more just? Once a test is available, shouldn’t it be accessible to any potentially affected person, period?

    Thanks for your thoughts!
    Elsa

    • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

      Thanks a lot for your comments.That is a good question Elsa.

      Who has the responsibility to inform Huntington´s families from Venezuela that there are genetic tests available? In my opinion Nancy Wexler should contact the local doctors or investigators who helped her to reach the families and collect their samples. They could and should inform the HD families.
      I also agree with you that everybody should have access to genetic tests or any benefit resulting from scientific research. As scientists, that is our goal. We want to help as many people as possible. But we want to be sure that those who were relevant for the research are not excluded. Would you agree with that?

      • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Elsa Youngsteadt

        Thanks! Yes, I absolutely agree that those who gave something to the research should not be excluded from its beneficial prodcts–ie the test. It’s just that when I turn it around a little bit in my head, and ask whom it WOULD be fair to exclude, the answer is: nobody.

      • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

        That is exactly the point. NOBODY should be excluded. That is our role. To make sure that this will happen.

        Thanks again Elsa.

  12. Marina Giovannelli

    Hi Mayana,

    I’m Marina Giovanelli, I reported that story on Huntington’s disease from Venezuela. My question is about the accuracy of genetic testing. How accurate are tests for genetic diseases such as Huntington’s or Alzheimer’s? Also, I understand there is a wide range in age of onset. To what extent can genetic tests predict the age a gene carrier will become symptomatic?

    Thanks!
    Marina

    • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

      Hello Marina

      For Huntington´s disease you can know for sure if a person has inherited or not the HD gene. If the father or mother have HD the chance that they will transmit the HD gene to each child is 50%. On the other hand it is known that the HD mutation is caused by an increase in a repeat region inside the HD gene (where a certain part of the genetic code repeats itself). People who have a greater repeat tend to have an earlier onset but this is also variable.
      On the other hand, for Alzheimer disease (AD), although there are also dominant forms, in most of the cases you may have “susceptibility” genetic variants but the environment plays an important role. It is very difficult to predict even if you carry such “risk genes” if you are going to develop AD. In short you cannot predict at what age a gene carrier will become symptomatic.

  13. Chery Cobb

    at-risk factors for carriers of CF?

    • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

      Hello Chery

      I am not aware of any risk-factors for CF female carriers. The only known risk is associated to male fertility. Some men who have inherited a mutation in the CF gene from one parent may be infertile depending on specific gene variations inherited form the other parent.

  14. Ruth Stanton

    Hello Mayana,
    I am a member of an HD family and I had never heard of the disease until I was 45 years old (and my children were 5 and 16).
    No I have not had my genes read. In my extended HD family the age of onset was 58+ years with my cousin’s CAG count in the ‘grey area.’

    Without an effective treatment, I personally would not test. The decision to test is strictly personal and I support my relatives whether they opt to test or not.

    Yes, I believe that companies that offer genetic tests should be regulated. This is an easy decision to make with Huntingtons Disease, but I’m not sure how I feel about regulating tests for Hemosiderosis or other less devastating disorders.

    • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

      Hello Ruth

      I agree with you. The decision to test for Huntington disease or any other condition is personal.

      However what we want to be sure is that people know exactly what is the meaning and benefit of being tested before taking any decision.

  15. Mitch

    I really enjoyed this podcast segment, and I like reading these discussions.

    This all reminded me of a short story I heard a few years ago, called “Results,” by Kristine Kathryn Rusch, published in audio format by Escape Pod (30 minutes):

    http://escapepod.org/2007/10/11/ep127-results/

    As I recall it’s about a near future world where people get genetic testing to see if they are a good match for each other to produce optimal qualities in their baby. The result is a society where people will choose dissolve a relationship rather than have a less than perfect child with each other. The story follows one woman and her struggle to decide what to do in light of her own results.

    It’s intelligent and provocative, and I recommend it to anyone interested in these matters.

    • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

      Hi, Mitch. I hope we will never get to this point.

      This is an issue that is frequently discussed when we talk about pre-implantation diagnosis (PGD). Today it is acceptable to select embryos free of genetic disorders, but what are the limits?
      Do you agree to select embryos just for gender? There are clinics that offer this possibility.
      And tomorrow will it be OK to choose babies for other “positive” traits such as ability for sports, eye colour, height, IQ, etc… Who will decide what and who should be selected?

      What is your opinion about this?

  16. Mitch

    One issue could be false positives or taking unnecessary preventative measures. If you discover that you have a genetic risk factor for a certain disease, should you spend your life worrying about that risk, even if it is only slight? Think about the issues with mammograms – many women undergo unnecessary measures due to a worrisome but ultimately harmless lump, though overall many lives are saved.

    I think that HD and CF are clear cut cases where you get the disease or you don’t, and where genetic testing can be straight forward. Testing specific genes makes sense, but I don’t know if sequencing your entire genome would be beneficial on the whole. You could end up with far more information than you know what to do with, especially if the answer is 20% increased risk, as opposed to 90%.

    • Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

      You are right, Mitch. For multifactorial conditions such as the risk for Alzheimer, heart conditions where the environment plays an important role I see more harm than benefit to know that you may have an increased risk.

      Sequencing the entire genome will be available at relatively low cost very shortly. Probably lots of people will want to have their genome sequenced. In practice we will generate a lot of information with very little knowledge. The genome sequencing of healthy older people (80 yrs old or more) will be extremely important to help us to interpret the results in younger people, that is, to sort out pathogenic mutations from genetic harmless variants.

  17. Error: Unable to create directory /home/worldsci/public_html//wp-content/uploads/2014/04. Is its parent directory writable by the server? Mayana Zatz

    Today is the last day of this Forum discussion. It was GREAT to have the opportunity to exchange ideas and talking to you.

    Thanks a lot!

    Mayana

  18. Very interesting report as well as the discussion that followed. I know that this issue will only become increasingly controversial as it genetic testing becomes more widespread.

  19. robyn

    in what cases do you think genetic screening should happen?

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