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The Science Behind Genetic Testing - Unlocking Your Genetic Code

By Medisys on January 14 2015 | News

What are genes, really?

Genes are the units of information that tell the body how to grow, develop, and function properly. Our genes often contain changes or variations which are part of what make us different from one another. Genetic variations are shared between members of the same family, which helps to explain why family members often share certain traits.

Sometimes genes contain harmful changes or "mutations", which causes them to not work as they should. These genetic changes can also be passed down within a family, which helps to explain why some health conditions such as heart disease, certain cancers, or hemophilia, run in families.


What is genetic testing?

Genetic testing is a medical test which looks at blood, saliva or other tissue samples to identify harmful genetic changes. In terms of complexity, genetic testing can be compared to searching the internet to find a single spelling error, thus it's not surprising that it can take several weeks or months to complete.


When is genetic testing useful?

Genetic testing is available for thousands of health conditions, such as sickle cell anemia, Huntington disease, and braca. Because many genetic conditions are rare, testing is typically offered only if you have a family history of a condition, or if you are from a part of the world where the condition is more common. Genetic testing may also be helpful in families where there are more cases of a particular diseases than usual, such as breast cancer, which may suggest an underlying genetic predisposition.  

Some people choose to have genetic testing to confirm a diagnosis, or to determine their own risk. Other people may choose to have testing while planning a pregnancy, to learn if a child may be at risk for a health condition that runs in their family.  For more information about genetic testing related to family planning, click here

More recently at-home, mail-delivery DNA test kits like “23 and me” have become available. These at-home DNA testing kits allow individuals to obtain information about their ancestry and also provide reports for certain hereditary health conditions such as Parkinson’s or Celiac Disease.


What are the different uses for genetic testing?

  • Help diagnose disease
  • Identify gene changes that may be responsible for an already diagnosed disease
  • Help determine the severity of a disease
  • Help guide doctors in deciding on the best medicine or treatment to use for certain individuals
  • Identify gene changes that may increase the risk to develop a disease
  • Identify gene changes that could be passed on to children
  • Screen newborn babies for certain treatable conditions

Genetic test results can be hard to understand, however specialists like geneticists and genetic counselors can help explain what results might mean to you and your family. Because genetic testing tells you information about your DNA, which is shared with other family members, sometimes a genetic test result may have implications for blood relatives of the person who had testing.


Why not test for everything?

Despite the mapping of the human genome more than a decade ago, it is not possible, nor helpful, to test all 20,000 genes. Scientists have only uncovered a fraction of the genetic contribution to many diseases and environmental and lifestyle factors are also known to play a role. While you may test negative for certain harmful genetic changes, other factors may still be at play.


Where is genetic testing available in Canada?

There are a wide variety of genetic testing centres in Canada, both within hospitals and within private healthcare centres. At this time, Medisys Preventive Health Clinics do not offer genetic testing services. It is important to note that genetic testing results may lead to emotional, social, or financial consequences. People may feel angry, depressed, anxious, or guilty about the results of genetic tests. In some cases, genetic testing may create tension within a family because the results can reveal information about other family members in addition to the person who is tested. 

It is also important to note that genetic testing can only provide limited information about an inherited condition. The test often can't necessarily determine whether or not a person will show symptoms of a disorder, how severe the symptoms will be, or whether the disorder will progress over time. Another major limitation of genetic testings is the lack of effective treatment for many genetic disorders once they are diagnosed.

If you are considering genetic testing for health conditions, it is advisable to consult a genetics professional who can explain in detail the benefits, risks, and limitations of a particular DNA test.