Hi Wade, and welcome. First of all, congrats on your son.
Usually, the testing process starts off with one or two sweat tests, and then, depending on those results, they draw blood for a genetic test. There is a lot of controversy over whether sweat tests are even accurate, but most insurance companies require them before they will pay for the genetic test. In the genetic test, they are looking for known CF gene mutations. There are over 1500 of them, so if you get the genetic testing, please make sure your doctor orders the full panel.
Does your son have symptoms of CF, or is this from a newborn screening? I'm just curious. I wish you the best. Please let us know what you find out.
Stacey