Comparison of normalized cFIX levels in hemophilia B dogs treated with AAV vectors of different serotypes. Average expression level of cFIX (ISD) during the experiment (since week 3; Table 1) was normalized based on the vector dose each dog received and presented as ng/mL/10¹² GC/kg. Error bars stand for standard deviation (± SD) of cFIX expression levels during the time period indicated in Table 1.