Understanding Genetic Testing


Genetic testing looks for changes, sometimes called mutations or variants, in your DNA.  Genetic testing is useful in many areas of medicine and can change the medical care you or your family member receives.  There are many different kinds of genetic tests.  Genetic tests are done using a blood or spit sample and results are usually ready in a few weeks.  Because we share DNA with our family members, if you are found to have a genetic change, your family members may have the same change.  Genetic counseling before and after genetic testing can help make sure that you are the right person in your family to get a genetic test, you’re getting the right test, and that you understand your results.


  • To learn whether you have a genetic condition that runs in your family before you have symptoms
  • To learn about the chance a current or future pregnancy will have a genetic condition
  • To diagnose a condition if you or your child has symptoms
  • To understand and guide your cancer prevention or treatment plan


Single Gene Testing
Single gene tests look for changes in only one gene.  Single gene testing is done when your doctor believes you or your child have symptoms of a specific condition or syndrome.  Single gene testing is also used when there is a known genetic mutation in a family.

Panel Testing
A panel genetic test looks for changes in many genes in one test.  Genetic testing panels are usually grouped in categories based on different kinds of medical concerns.  Panel genetic tests can also be grouped into genes that are all associated with higher risk of developing certain kinds of cancer, like breast or colorectal (colon) cancer.

Large-scale Genetic or Genomic Testing
There are two different kinds of large-scale genetic tests:

  • Exome sequencing – looks at all the genes in the DNA (whole exome) or just the genes that are related to medical conditions (clinical exome)
  • Genome sequencing – the largest genetic test, looking at all of a person’s DNA, not just the genes


The test found a genetic change known to cause disease.

The test did not find a genetic change known to cause disease.  Sometimes a negative result occurs when the wrong test was ordered or there isn’t a genetic cause for that person’s symptoms.  A “true negative” is when there is a known genetic change in the family and the person tested did not inherit it.  If your test results are negative and there is no known genetic change in your family, a negative result may not give you a definite answer.  This is because you might not have been tested for the genetic change that runs in your family.

A variant of unknown or uncertain significance means there isn’t enough information about that genetic change to determine whether it is benign (normal) or pathogenic (disease causing).

Source:  www.cdc.gov