The next time you visit the doctor for a checkup, they may not need a vial of your blood. A sample of your spit might be all your doctor needs. Check out the following video from Inside Science TV from the American Institute of Physics.
https://youtu.be/HtKLCbvRg5E?list=PLPe4mEu2EKttKkwVnVkJOstwnaOUBCLTO