Although use of the term “comprising” in a claim preamble does not render every word and phrase in the claim open-ended, similar language attached to a particular claim limitation in the body of the claim may expand the breadth of that limitation beyond the scope enabled by the specification. Here, for example, the claimed “set of … loci … comprising” a list of particular multiplexes was found to encompass a virtually unlimited number of loci and therefore lack enablement in an unpredictable field of technology. “[The patentee] has chosen broad claim language at the peril of losing any claim that cannot be enabled across its full scope of coverage.” It may therefore be best to avoid open-ended transitional phrases for key limitations in the body of a claim, especially in unpredictable fields of technology.
Background / Facts: The patents being asserted here are directed to DNA sequences called “short tandem repeats” (STR). The region of the DNA strand in which they occur is called an STR “locus.” In this regard, the claims recite multiplex amplification of “a set of … loci … comprising” a list of particular STR loci multiplexes of varying complexity, ranging from a 3-plex to a 14-plex. Both parties agree that the claims require successful co-amplification of every locus in the claimed “set of … loci.” It is also undisputed that, in this field of technology, introducing even a single STR locus to an existing loci multiplex significantly alters the chemistry of, and has an unpredictable effect on, whether the resulting multiplex will successfully co-amplify.
Issue(s): Whether the open-ended list merely “comprising” certain loci renders the claims invalid for lack of enablement across the full scope of the claimed invention under § 112, ¶ 1.
Holding(s): Yes. “[W]e disagree with [the patentee’s] characterization that unrecited STR loci combinations in the ‘open loci set’ limitation of the asserted claims are merely ‘unrecited elements’; under the undisputed claim construction, they are part of the claim scope. … While the term ‘comprising’ in a claim preamble may create a presumption that a list of claim elements is nonexclusive, it ‘does not reach into each [limitation] to render every word and phrase therein open-ended.’ [] [The patentee’s] claims differ from customary ‘open-ended’ claims in that [the patentee’s] usage of ‘comprising’ in its ‘open loci set’ limitation, as construed, expands the claims at a key limitation in order to cover what are indisputably advances in this unpredictable art. Under the circumstances here, the numerous embodiments covered by [the patentee’s] claims cannot be merely regarded as ‘unrecited elements’ in a standard ‘open-ended’ claim.”