Tumor Genetics Blog

By Davide Berta

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Thanks to the great improvements in genetics, including the sequencing of thousands of variations in DNA that can predispose us to syndromes or diseases, commercial home genetic testing kits have become more and more popular. The general principle of genetic testing is simple: a DNA sample is taken (usually from saliva), and analyzed to verify the presence of any variation that predisposes for a disease. In a clinical setting, this can be very useful in preventing the disease, when possible, or to prepare to cure it in the best way. With commercial testing kits, the same principle applies: you send away your saliva samples and you are mailed your results. It sounds easy and useful, right?

But what exactly is the information that we obtain from a commercial genetic test?

Is it really only a positive/negative result? Who benefits the most from a genetic test? Are there social and psychological concerns regarding home testing? These questions can raise the issue concerning the ethics of genetic testing purely out of curiosity. In 1998, the World Health Organization provided some general guidelines, the major points of which are: 1) people should be properly informed before taking a genetic test and 2) after being informed, they should be free to accept or refuse it.

Who should undergo a genetic test?

A genetic test is recommended for adults at risk of developing some hereditary disease, although willingness in asymptomatic adults (a person at risk but yet to show symptoms) varies a lot. Willingness to undergo a test increases if there is a possibility to prevent the disease. Instead, for incurable diseases less than 20% of all those at risk take the test.

Psychological concerns: I took a home genetic test, what then?

One person chooses to undergo a genetic test. How will this person deal with the result? Several studies have tried to answer this question, and the outcome is not as obvious as you may expect. For example, people at risk for an incurable disease are not always devastated after finding out they carry the predisposing genetic variation; conversely, in some cases, a person at risk who receives good news can show an increase in psychological stress. Sometimes it may be better just not to know the result of a genetic test, because the result could affect relationships with relatives and family dynamics.

There is also an issue that concerns the reliability of at-home genetic tests. To make the story short, a test is not infallible and it could provide a false positive result. This means that patients may think they carry a variation in the DNA sequence that predisposes them to a genetic disease, when instead the result is just wrong. For example, a recent study reported that 40% of the studied variants were false positives, and this is why genetic testing should be performed in a clinical environment with the support of a specialist, which brings us to the next point.

Social concern: Who will know about the result of my test?

A person who undergoes genetic testing should be the only one with the right to own the information, and to decide whether third parties are allowed to access the data. Privacy is a complex issue nowadays. We experience it every day with the conditions we are forced to accept on websites. With our genetic data, this must not happen. No one should force you to sign some privacy agreement without you being fully aware of what you agree to, and no one should exploit your data without your consent.

Let’s now see what the informed consent is…

Informed consent is the process to get permission to begin a healthcare-related procedure, including genetic testing. Informed consent is based on the principles of right to autonomy and self-determination. However, autonomy is never an individual-related issue, because we share parts of our genome with our relatives. Take for example the case where authorities in the US used a commercial genetic genealogy platform to find a suspect by identifying his relatives. Usually an informed consent contains general information about how the test is performed, what the result means, potential physical or emotional risks, how and to whom test results will be reported. Other considerations include whether the results can be used for research purposes, what happens to the specimen after the test, and the possibility that it could provide information that can affect other family members’. Informed consent must be signed by the patient upon full understanding of the aforementioned conditions.

Is genetic testing just for disease predisposition?

Not really. One of the main purposes that push people to do a genetic test is to learn about ancestry. Other genetic companies sell specific diets and fitness plans, improved on the basis of specific genetic tests. Again, some companies sell tests for children to learn about their potentialities (e.g.: in sports).

Are these tests worth it?

In my opinion, I would say no for two reasons. First, remember the privacy issue (these companies will own and store all your most private information, which is much more than what Apple or Microsoft can get from your internet history). Second, a genetic test is not mathematics. No genetic test can tell with accuracy what the best diet is for you or what career your child should take. Genetic testing is not a game, and should be taken seriously and not as a tool to satisfy curiosity.

If you would like to read more from Davide, you can visit his blog: In Science We Trust.