On February 5, 2026, a Patent Trial and Appeal Board panel reversed an improper-Markush rejection in Ex parte Chowdhury, Appeal 2025-002261, application 17/005,548. The Office designated the decision informative on August 25, 2026. The panel was Katz, Flax (author), and Hardman. Real parties in interest are Dana-Farber Cancer Institute and Albert Einstein College of Medicine. Claims 60, 66, 67, 88, 90-95, and 101-104 were on appeal.
The holding
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. Species may be structurally divergent if they are substitutable for that function.
The claim context
The claims are directed to a method of treating radiation-induced damage using serum miRNA levels as quantifiable markers. Representative claim 60 recites determining a first serum level of one or more recited miRNAs, administering a treatment selected from a Markush group of therapies, determining a second miRNA level, and continuing or switching treatment based on whether specified miRNAs rise or fall. The Board treated the recited miRNAs as markers that can stand in for one another, not as a set of structurally unrelated compounds. A section 101 rejection had been withdrawn; only the Markush rejection was on appeal.
What it means in practice
Practitioners who draft or examine Markush groups in diagnostic and method claims should expect this informative designation to be cited on both sides of the MPEP 2117 fight. It is a Board decision, not Federal Circuit law.
What to watch next
How the examining corps applies the designation, and whether it gets cited outside the diagnostic-marker setting in which it was decided.