In Roche Molecular Systems, Inc. v. Cepheid, the Fed. Cir. affirmed the district court’s decision that claims directed to a detection method of Mycobacterium tuberculosis using specific DNA primers having a 3-prime and a 3-prime hydroxyl group and to specific DNA primers were patent ineligible.  Citing In re BRCA1, the primers were not distinguishable from the isolated DNA found patent-ineligible in Myriad.  Structural identity of the sequence was focused on as indistinguishable from the corresponding nucleotide sequence on the naturally occurring NTB rpo B gene.  It was noted that the BRCA1 primers had 3-prime ends and 3-prime hydroxyl groups, exactly as Patentee’s primers.  Patentee argument that the naturally occurring chromosome was circular without a 3-prime end nor a 3-prime hydroxyl group and therefor different from the linear molecule was dismissed as directed to shape not sequence.  Finally, Patentees argument as to identification of fingerprint primers allowing for unique identification of Mycobacterium tuberculosis was dismissed as nothing more than a natural phenomenon.  Claims to the method of detecting were dismissed as directed to a natural phenomenon.  Judge O’Malley wrote a concurrence that their decision in BRCA1 required a conclusion of patent ineligibility but that their holding should be revisited as unduly broad, having been decided on procedure and a record which was insufficiently developed.  The concurrence makes a good argument that primers have a structure which is not naturally occurring.