The Pros and Cons of Genetic Testing

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What Are the Uses for Genetic Tests?

Female scientist examining DNA gel in laboratory for genetic research
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Introduction to Genetic Testing

As scientific and medical discoveries help us better understand how our genetic make up affects our bodies and our health, new tests are also being developed to help individuals know whether their genes align with certain diseases or conditions. People have begun to wonder whether they should undergo genetic testing. That decision can be made by understanding what genetic testing is all about, and reviewing the pros and cons of genetic testing.

Why Are Genetic Tests Developed?

For thousands of years, human bodies have developed diseases or conditions with very little knowledge about why. Why does one woman develop breast cancer, but another one does not? Why does one man develop Parkinson's Disease, but another does not? While environmental factors could tell part of the story, it was recognized that there must be something about that person's body that contributed to development of these medical problems, too.

Early development of medical science was mostly aimed at making sure diseases and conditions could be cured or healed. During the past 50 or 60 years, science began looking at a person's genetic make up as a way to answer more fundamental questions about why humans varied in their development of these kinds of problems.

Other human body questions developed over time, too, often in response to legal questions. Questions like, who fathered a particular baby? Or whose blood was found on a murder weapon?

Beginning in the 1950s and 60s when DNA was discovered as the basis of human cells, and genes were discovered as the basis for DNA and heredity, and therefore no two human beings had exactly the same genes or DNA, scientists realized they could begin to answer some of those questions. For example, if they examined the genetic makeup of a group of people who had the same disease, they could come to some conclusions about the similarities of their genes, and why their genes were different from someone who did not have that disease. Or, if they mapped someone's DNA, they could compare it to someone else's DNA and know whether the two people were related.

By 2003, the Human Genome Project was completed, and scientists were able to identify every gene in a human's body. Other scientists began pairing them with the medical problems they cause. Among the earliest disease-identifiable genes were the BRCA genes, known to influence development of breast cancer. More new gene-disease identifications are being made every day.

As these pairings are discovered, scientists can begin to see how they influence development of disease or conditions, and can, hopefully, someday then develop ways to stop those genes from their destiny of creating those medical problems. These are the early days of personalized medicine. Personalized medicine means a person's genetic makeup is what influences either preventive steps to avoid disease, or drugs or other medical treatments that are tailored to a person based on their genetic makeup.

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What Types of Genetic Tests Exist?

Some genetic tests have been around for decades. The testing of blood, saliva, hair and skin has been done for decades to determine everything from "whodunnit?" to paternity.

Others have been in use for several years. Genetic screening tests may take place before a baby is conceived to make determinations about whether parents' offspring will be prone to develop certain diseases or conditions. Prior to insemination, a woman and man will both undergo genetic testing to determine whether or not their baby will develop a genetic disease like cystic fibrosis, Sickle Cell or Huntington's Disease. Once they know the chances, they can better determine whether they should conceive that baby.

Today new tests are being developed for many types of diseases that may improve our knowledge of our health histories and possibly predict our health futures. Tests have been developed to determine someone's risk for developing Alzheimer's Disease, high blood pressure or lung cancer, or for example. These kinds of tests are in their infancy, and for most, scientists disagree on their accuracy.

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Why Are There Questions About the Pros and Cons of Genetic Testing?

There are very few questions about the reliability of genetic testing for blood evidence, parent identification or pre-natal determinations because they are quite definitive and have already proved themselves to be useful.

Questions arise for those tests which have not yet proven their value. Even when a gene can be aligned with a certain disease, and even if it can be determined that someone possesses that version of a gene, that does not guarantee that person will develop the disease. Even if it could prove someone will develop the disease, there may be no way to alter that development or even treat them if they do develop it. Those are factors which influence the tests' value.

Scientists and researchers are definitely interested in making sure genetic testing takes place as they develop more and more approaches to personalized medicine. The more testing that takes place, the more evidence they have for procedures, processes, and treatments that may or may not work.

But today, there is little medical value for patients to have their genes tested in regards to future disease development. There are a few exceptions - those aimed at identifying breast and other female cancers, for example. Over time, new, more definite tests and next steps will be developed for even more diseases and conditions.

Therefore, questions arise about whether or not someone should have their genes screened for these types of diseases today. You'll want to be aware of the pros and cons to genetic testing.

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What Are the Pros of Genetic Testing?

For those tests that are already in regular use, like paternity or pre-natal genetic testing, there are well-document positive outcomes. They put people in control of information that helps them make solid decisions about their future - medically, financially and legally. Having that kind of definitive knowledge is a definite pro for many people.

This is also true for those genetic tests that are in use for some disease predictions, such as the BRCA testing. Women who learn they have specific indicators and a good chance that they will develop the disease can make decisions based on that knowledge.

And that is the most important "pro" for any genetic testing -- knowledge. If you are someone who just wants to know about possibilities so you can make decisions, then you might want to have the testing. For example, you might be tested for genetic markers for Alzheimer's Disease. If you learn your body will have a tendency to develop Alzheimer's Disease, you might make preventive choices in your younger years to give yourself the best chance of not developing it.

One other positive outcome is that by having your genes screened, your information will be put into a database of information which can be shared by researchers and scientists around the world. They are learning more about how to use this information to develop treatment to help our children, their children and so forth in the future. In fact, some people are willing to undergo testing simply to further science, in hopes it will benefit their descendants.

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What Are the Cons of Genetic Testing?

Because most of the world of genetic testing and personalized medicine is so new, there are still many questions it cannot address. Also, since most genetic testing only raises more questions, instead of providing answers, it may actually create more problems than it solves. Further, there are a number of legal and ethical implications surrounding genetic testing, most of which lean toward the negative.

Here are the questions which suggest those potential problems:

How accurate are the tests? There are no accuracy measures in place for most, in particular those that predict your health future. Say you are tested for the potential for lung cancerĀ and learn that you might develop it someday. You decide not to smoke and you don't develop it. But you can't know whether the test was right or wrong to begin with because you took steps not to develop it.

Who can translate the information? A doctor may order a certain genetic test for you, or you may order one yourself on the Internet, or even purchase one in a store. Who can review the results for you? Geneticists are trained to do that translation, and as long as you spend time with one to learn what the results mean, you may learn something from them. But most doctors are not trained to understand them. If the results arrive in the mail, you'll have to do your own research to understand the answers.

Of course, the paperwork will also include disclaimers that accuracy cannot be guaranteed. Further, there could be mistakes in the testing itself.

Who owns genetic information? It may be owned by you, the patient, but it's being controlled by others. Or it may be owned by the test developers, in which case they can do what they want to with it - keep it, sell it, share it - whatever they want. There are very few laws that affect genetic information so far. The laws that do exist, GINA, address discrimination and genetic code only.

How private is the information? Because testing is so new, laws do not yet exist to determine how the information can be used, and therefore even whether HIPAA privacy and security laws would be applied.

What will you do with the information? Few of these disease-prediction tests produce actionable results, with the possible exception of prevention tactics like managing one's weight, not smoking, getting plenty of exercise and others - all good steps regardless of the results of a gene test. Nor are there suggested treatments for the great majority of these tests -those tests which will eventually result in personalized approaches for patients. With few exceptions, those personalized treatments just aren't available yet.

As time goes on, more tests will be developed, more laws will be created to address them, and personalized medicine will become an effective approach to treating human beings for medical problems. But for now, patients must review the pros and cons of genetic testing for themselves to decide whether it is the right step for them.

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