I Don't Believe in Imaginary Property
writes "Doctor's groups, including the AMA and too many others to list, are supporting the Mayo Clinic in the case Prometheus v. Mayo. The Mayo Clinic alleges that the patents in question merely recite a natural phenomenon: the simple fact that the level of metabolites of a drug in a person's body can tell you how a patient is responding to that drug. The particular metabolites in this case are those of thiopurine drugs and the tests are covered by Prometheus Lab's 6,355,623 and 6,680,302 patents. But these aren't the only 'observational' patents in medicine — they're part of a trend where patents are sought to cover any test using the fact that gene XYZ is an indicator for some disease, or that certain chemicals in a blood sample indicate something about a patient's condition. There are even allegations that certain labs have gone so far as to send blood samples to a university lab, order testing for patented indicators, then sue that university for infringement. Naturally, Prometheus Labs sees this whole story differently, arguing that the Mayo Clinic will profit from treating patients with knowledge patented by them. They have their own supporters, too, such as the American Intellectual Property Law Association."
Prometheus doesn't seem to be a classic patent troll; they actually perform the tests for which they have obtained patents.