Hepatic gene targeting of the mouse albumin locus results in phenotypic correction of hemophilia B. (A) Schematic illustrating albumin targeting strategy. (B) Cel I nuclease assay from liver DNA measuring ZFN-induced indels within albumin intron 1. Lanes represent individual mice at day 7 after AAV8-ZFN treatment. (C) hFIX in mouse plasma after treatment with AAV8-hF9-donor and either AAV8-ZFN (blue circles) or AAV8-hF9-ZFN (green diamonds) with a target sequence not present in the mouse genome; n = 3 mice per group. (D) hFIX levels at week 2 after treatment are proportional to AAV dose (1:5 ZFN to donor). Gray bar: normal levels. Points represent individual mice. (E) hFIX levels in hemophilia B mice 2 weeks after treatment with AAV8-mAlb-ZFN and AAV8-hF9-donor (n = 4 mice per group). *P = .029, Fisher's exact test. (F) Clot formation in mice depicted in panel E, measured by aPTT prior to and 2 weeks after treatment. The aPTTs of wild-type mice are shown for comparison. **P < .01, 2-tailed Mann-Whitney test. HDR, homology directed repair; n.s., nonsignificant; SA, splice acceptor.