Fig 1: In Vivo ZFN-Mediated Insertion of hIDUA at the Albumin Locus Results in Expression of Active Enzyme in MPS I Mouse Hepatocytes(A) Outline of targeting strategy at intron 1 of albumin. Hom, arms of homology to mouse albumin locus; pA, polyadenylation sequence; SD, splice donor site; SA, splice acceptor site. (B) Percent insertion and deletions (% indels) at the ZFN target site in mouse liver 1 or 4 months post-treatment. Each symbol represents an individual mouse, and mean ± SD is shown. (C) IDUA enzyme activity in protein extracts from mouse liver tissue 1 or 4 months post-treatment. Dashed line indicates approximate limit of detection for the assay (0.2 nmol/hr/mg). Data are shown as mean ± SD. *p < 0.05, when compared to the gender-matched untreated MPS I group. n = 3 per group at 1 month and n = 4–5 per group at 4 months. (D) Expression of hIDUA in mouse liver protein extracts 1 or 4 months post-treatment. Each lane represents an individual mouse. GAPDH is shown as a loading control.