Schematic diagram shows the Cas9 target site located on exon 2 of the mouse FIX locus. Following homologous recombination with the AAV donor vector containing partial complementary DNA of codon-optimized hFIX-Padua, a chimeric FIX messenger RNA is transcribed from the modified FIX locus which is then translated to a chimeric FIX protein. See Figure 1 in the article by Wang et al that begins on page 2745.