Board rules that a "precise" correlation between structure and function must be established to satisfy written description requirement for nucleic acid claims

October 7, 2011 – Blog Post

One of the rejections at issue in Ex parte Wei and Zhang (Appeal 2010-010989, Application 12/283,347) is a written description rejection under 35 U.S.C. §112, first paragraph. The claims of this application are directed to an isolated nucleic acid and a recombinant host cell. The Examiner concluded that Appellants’ specification failed to provide written descriptive support for the claimed invention.

Claim 11 is representative of the claims of this application and is as follows:

An isolated nucleic acid comprising a p49/STRAP gene and adapted to express a p49/STRAP protein from the p49/STRAP gene in a recombinant host cell.

Appellants’ specification defined a p49/STRAP gene as a nucleic acid that encodes a p49/STRAP protein, and also defined a p49/STRAP protein as a protein that (i) has an amino acid sequence that is at least 40% identical to both SEQ ID No:1 and SEQ ID No:2 and (ii) binds in vitro and in vivo to the COOH-terminal portion of serum response factor (“SRF”). The Board indicated no doubt with respect to the written descriptive support for a p49/STRAP protein that satisfied part (i) of the definition. However, the same cannot be said for part (ii).

In light of the chemical/biochemical nature of the claimed invention, the Board began its discussion of the case by noting that “A chemical genus can be described by structural description of a representative number of the species within the genus or by describing ‘structural features common to the members of the genus, which features constitute a substantial portion of the genus.’” (citing to University of California v. Eli Lilly and Co., Fed. Cir. 1997).

The Board also noted that “[t]he structural description does not necessarily require disclosure of the compound’s complete chemical structure: the written description requirement can be met by ‘show[ing] that an invention is complete by disclosure of sufficiently detailed, relevant identifying characteristics … i.e., complete or partial structure, other physical and/or chemical properties, functional characteristics when coupled with a known or disclosed correlation between function and structure, or some combination of such characteristics.’” (citing to Enzo Biochem, Inc. v. Gen-Probe Inc., Fed. Cir. 2002).

Given the preceding case-law, the Board stated that the question at hand in this case was “have Appellants identified a structure that correlates to the required function, so that a person of ordinary skill in this art would recognize which nucleic acids in the larger genus encode a protein having the required function, and constitute the claimed smaller genus?” The Board decided that Appellants’ disclosure did not provide a sufficient correlation between structure and function to permit the skilled artisan to “envision nucleic acids meeting claim 11’s requirement to express a protein that (1) is at least 40% identical to both SEQ ID No:1 and SEQ ID No:2 and (2) binds the COOH-terminal portion of SRF.”

This decision was based on the disclosure of Appellants’ specification, namely that the specification only disclosed that the structure required to fulfill p49/STRAP’s function in binding the COOH-terminal portion of SRF is either in the 135 amino acid region encompassing residues 53-185 or in the 91 amino acid region encompassing residues 1 to 91 of the p49/STRAP protein. As such, the Board stated that “it is unclear what precise region of p49/STRAP correlates to its function in binding the COOH-terminal portion of SRF.”

Accordingly, in this case the Board has taken the position that when Appellants choose to rely upon certain identifying characteristics of a compound/protein, rather than a complete chemical structure thereof, in order to meet the written description requirement of 35 U.S.C. §112, 1st paragraph, a “precise” correlation between structure and function must be established. As the Board’s decision implies, identifying possible alternative correlations between structure and function is not necessarily sufficient to meet the written description requirement in these types of cases, even when those alternatives are limited to only two.