USPTO Designates Informative Markush Grouping Decision

The U.S. Patent and Trademark Office designated Ex parte Chowdhury as informative on September 2, 2026. The decision, originally issued by the Patent Trial and Appeal Board on February 5, 2026, reversed an examiner's rejection of claims reciting multiple miRNA biomarkers.

The Board held that a Markush grouping is proper if it recites members of a subgenus and the specification describes those members as performing similar functions in the context of the invention. The ruling emphasizes similarities in function over strict structural identity.

Applicants facing similar rejections may now cite the decision when challenging examiner findings. The designation provides guidance without creating binding precedent.

The underlying application concerns methods for using miRNA biomarkers to assess efficacy of treatments reducing radiation-induced damage.