Diagnosis and Testing
What is the difference between tumor testing and germline testing?
There are key differences between analyzing the DNA from a tumor and analyzing DNA from your blood. It is not uncommon now to have DNA analysis (DNA sequencing) performed on a tumor sample. Outcomes can sometimes affect treatment options. Most of the genetic changes found in a tumor sample are new (somatic) changes. Somatic mutations are not present at birth, but rather they arise randomly later in life. Many somatic changes are made during the growth of a tumor. MLH1, MSH2, MSH6, PMS2, or EPCAM gene mutations found in a tumor does not confirm that a person has Lynch syndrome.
Lynch syndrome is caused by germline mutations. These are genetic changes that we have in our DNA from birth, and we expect to find them in every cell in our body. DNA sequencing on blood or saliva samples can detect these germline mutations.