In Athena Diagnostics v. Mayo Collaborative Services, the Fed. Cir. affirmed the District Court’s holding of invalidity under 101 directed to a law of nature and lacking an inventive concept.  Patentee had discovered that the 20% of patients exhibiting the symptoms of the neurological disorder Myasthenia gravis (MG) but who did not express acetylcholine receptor autoantibodies, produce autoantibodies to the membrane protein MuSK.  Patentees discovered a correlation of autoantibodies to MuSK, a protein with no prior association with any disease, with MG.  The claimed invention of a diagnostic method using a labeled man-made compound was held to be directed to a law of nature which correlated the presence of naturally occurring antibodies with a disease.  The Fed. Cir. reaffirmed that use of a man-made molecule in a method claim employing standard techniques to detect or observe a natural law may still leave the claim directed to a natural law.  Judge Newman dissented recognizing that the claims are directed to a multi-step method of diagnosis, not a law of nature.  Claims to an assay kit comprising MuSK and means for contacting with bodily fluid were restricted and not pursued.  Claims were never presented to the man-made molecule.