A set of patent claims for a DNA preparation method cleared the hurdle of subject matter eligibility at the Court of Appeals for the Federal Circuit last week, even though the technology relates to a diagnostic method.

In Illumina, Inc. v. Ariosa Diagnostics, Inc., the claims involved extracting DNA from a maternal blood sample, then selectively removing larger extracellular DNA fragments from the sample. The claimed method hinged on the principle that maternal blood contains some extracellular fetal DNA, and that most fetal extracellular DNA in a maternal blood sample is about 500 base pairs or less, while the maternal extracellular DNA is usually about 500 base pairs or more.

This technology should sound somewhat familiar to those who have followed subject matter eligibility for diagnostic methods. It relates substantially to the technology at issue in Ariosa Diagnostics, Inc. v. Sequenom, Inc., a case well-known as the first among several Federal Circuit decisions finding diagnostic methods ineligible. The court acknowledged this relationship in the opinion.

Similarities to the earlier case notwithstanding, the Federal Circuit found in favor of eligibility last week. Notably, the majority opinion declared that “This is not a diagnostic case. ... It is a method of preparation case.” Considering the underlying principle of the different sizes of maternal and fetal extracellular DNA in the sample, the Federal Circuit found that the claims are directed to a patent-eligible method of utilizing this principle to separate maternal and fetal DNA, not directed to the principle itself. This analysis appears to align with Step 2A, Prong 2 in the USPTO’s eligibility guidelines of 2019. The court emphasized that the method changes the composition of a sample in a concrete way, going beyond mere observation of size differences. Distinguishing the claims over those in the earlier Ariosa case, the court instead compared the claims to those in Rapid Litigation Management Ltd. v. CellzDirect, finding that the inventors indeed discovered a natural phenomenon, but then used it to invent a patentable method.

“This is not a diagnostic case. ... It is a method of preparation case.”

- Illumina, Inc. v. Ariosa Diagnostics, Inc.

Judge Reyna, who wrote the majority panel opinion in the 2015 Ariosa v. Sequenom case, dissented from the majority last week. The dissent focused heavily on analysis of the “claimed advance” of the preparation method, which the dissent said was merely the difference in size between maternal and fetal extracellular DNA. Judge Reyna found the majority opinion lacking in any analysis of the “claimed advance.”

The divided panel in this case continues the story of uncertainty for the subject matter eligibility of diagnostic technologies. As a precedential case, Illumina v. Ariosa may set the tone in future life sciences subject matter eligibility inquiries, unless the Supreme Court or en banc Federal Circuit later disagrees with the majority analysis here.