“The principal issue presented is whether the district court erred in limiting the terms ‘branched alkyl’ and ‘branched C10-C20 alkyl’ through lexicography to require one carbon atom in the group to be bound to at least three other carbon atoms, where the claims are not so limited, and the specification and prosecution history specify numerous examples of branching where a carbon atom is bound to two or three other carbon atoms.”
“We conclude that Alnylam acted as lexicographer in its requirement of a carbon bound to at least three other carbons ‘[u]nless otherwise specified’ and that Alnylam did not otherwise specify for purposes of the asserted claims.”
