Markers of coagulation activation in WT C57BL/6 mice expressing hFIX-WT and hFIX-Padua at supraphysiologic levels following AAV. Mice expressing hFIX-WT (white bars) and hFIX-Padua (black bars) at levels resulting in (A,C) 100% to 230% activity and (B,D) 480% to 2020% activity were assessed for (A,B) thrombin antithrombin complexes (TAT) and (C,D) d-dimers as markers of coagulation 2, 5 (TAT only), and 8 months following vector administration. At no point were there statistically significant differences between the hFIX-WT– and hFIX-Padua–expressing groups. Gray bars, empty capsid-treated control animals with normal FIX levels.