DNA tests are done for a variety of different reasons. In all instances, a DNA test is done to look for a specific gene or chromosome that is thought to be associated with some condition or problem you are having. In other words, they are not done routinely, and not all genes are tested when a DNA test is done.
The way a DNA test is done depends on what is being tested. For example if you have a tumor or another growth of some type, a biopsy
will be done of that tissue to be viewed under a microscope. Depending on what is found, DNA tests of that tissue may be carried out. Another instance in which DNA testing is done is if there is suspicion that you have an abnormal gene. If you have symptoms that have gone unexplained, or if there is a disease that your doctor
is trying to diagnose, then you may need tests of your DNA. If this is the case, a simple blood test can be done. There is no scan that can be done for a DNA test.
I suggest that you pose this question to your primary care physician
. If you are going for a DNA test, he or she can explain why this is being done, and the methods used to do it. Good luck.