Targeting of albumin locus promotes stable supraphysiological activity of GBA in mouse plasma. (A) GBA activity as determined by enzymatic activity assay in wild-type mice 3 weeks after treatment with either 1.2 × 10¹² vg AAV8-GBA donor alone (red circle) or in combination with 1.5 × 10¹¹ vg of each individual AAV8-ZFN (green circle). Untreated wild-type mice (▪) shown as controls. (B) Time course of GBA activity in the mice treated in (A). **P < .01, 2-tailed Mann-Whitney test comparing ZFN + donor group to untreated or donor only groups.