Immunofluorescent staining for human F.IX in livers of wild-type and transgenic mice. Original magnification ×200. (A) C57BL/6 mouse. (B) Mouse with severe hemophilia B due to targeted disruption of F.IX gene.7 (C) Mouse transgenic for human F.IX early stop variant. hF.IX is not detected. (D) Mouse transgenic for hF.IX late stop variant. F.IX protein is detected at levels comparable to those seen in the wild-type line (panel H). (E) Mouse transgenic for hF.IX carrying missense mutation (R180 → W). Line MS-2 has high circulating levels (8-10 μg/mL of mutant hF.IX protein. (F) Line MS-12, same transgene as in panel E, but lower circulating levels (0.5 μg/mL-1.6 μg/mL). (G) Mouse transgenic for Chapel Hill mutation, G381 → E (cCH-4 line, no detectable circulating F.IX levels). (H) Line WT-2, mouse transgenic for wild-type hF.IX, with circulating levels in normal range (3 μg/mL-5 μg/mL). (I) Line WT-14, mouse transgenic for wild-type hF.IX, with circulating levels in the supranormal range (20 μg/mL-40 μg/mL). (J) Map of construct used to generate transgenic mice. The human F.IX cDNA (or variants thereof) is interrupted by a 300-bp fragment of intron 1. Expression is driven by the murine transthyretin promoter, and an SV40 polyadenylation signal is added at the 3′ end.
