Exonhit Therapeutics v. Jivan Biologics, Inc. (PDF) 2008 U.S. Dist. LEXIS 24314 Decided March 7, 2008 Judge Alsup Judge Alsup construed “region of variability” to mean “a segment of DNA within a gene or gene product that serves one role (exon, intron, exon-intron junction or exon-exon junction) with respect to one isoform of the gene product and a different role with respect to another isoform of the gene product.”