What To Expect When You’re Testing Your Genetics

Once you have decided to go ahead with a genetic test, your doctor or nurse practitioner or medical geneticist will order or administer that test, collecting a sample of amniotic fluid, blood, skin or other tissue.  This sample will then be sent on to a lab for analysis.

Here are the common procedures:

  • Cheek swab.  A simple swab sample from the inside of your cheek (back near the tonsils) is collected in some cases (think of all those crime dramas on TV – they are forever swabbing cheeks!).
  • Blood sample.  This sample is generally obtained by inserting a needle into a vein in your arm.  When ordered for screening a newborn, the sample is drawn from the baby’s heel.
  • Amniocentesis. This is a prenatal genetic test that involves analyzing a sample of the amniotic fluid.  A doctor inserts a very thin, hollow needle through the abdominal wall into the uterus and then withdraws a small amount of the amniotic fluid into a syringe.
  • Chorionic villus sampling. Another prenatal genetic test, this one involves taking a tissue sample from the placenta.  The sample may be taken with a catheter through the cervix or through the abdominal wall and uterus with a very thin needle.
Now you wait for the results.  The time it takes to get a report back depends on the type of test you have had as well as your health care facility’s procedures for follow-up meetings.  We reminded you yesterday to ask about how long the results might take before you undergo the screening procedure – it will make it less stressful if you know what to expect.   As a rule, the testing lab will return the results to your doctor and he or she, in turn, will then go over them with you.
What the results might mean:
Positive results.  If your report comes back as ‘positive’, it indicates that the genetic change or alteration that was tested for was found.  What does this mean?  That would depend entirely of what prompted the genetic test is the first place.   If your doctor was trying to pin down a specific condition or disease, this positive result will help your health care team decide on the right treatment plan.  Ask your doctor what a positive result means to you, specifically.  Are you looking at a lifestyle change to manage the risk?  Do you need to think about career changes or health insurance options?  The more you know and understand, the better.
If you took the test while perfectly healthy, a positive test does not mean that you will get a certain disease or disorder, but it does give your doctor information about going forward, looking into new developments in the detection, treatment and prevention of a potential risks.
If you were tested as a carrier, seeing if you are carrying an altered gene that may be inherited by your children, a positive result gives your doctor or a genetic counselor more information to use in determining the actual risk your children run of developing a disease.  This information, in turn, can help you and your partner with family planning.
Negative results. When a test comes back as ‘negative’ it means that the genetic change or alteration tested for was not found.  Of course, this does not mean with 100% accuracy that you do not have an alteration.  Test accuracy varies and all genetic defects are not detectable.  A negative result does not in any way, shape or form guarantee that you won’t someday develop the illness or condition.
Inconclusive results.  This is probably the result we all hate the most.  Maybe a follow-up test will be in order, but there are cases where a genetic test simply cannot provide the help we need about a specific gene.  Remember, too, there are lots of gene variations that don’t affect our health, so figuring out which gene alterations cause disease and which ones are entirely harmless is very, very challenging.  Again, it is important to go over results with your physician or counselor.  Keep asking questions until you are sure you understand what the findings might mean for you and your family.
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