FIGURE 1.

FVIII activity measured by the chromogenic substrate assay for participants in the 6 × 10¹³ and 4 × 10¹³ vg/kg cohorts over 5 and 4 years, respectively. FVIII activity levels taken within 72 h of exogenous FVIII administration were excluded. FVIII activity that fell below the lower limit of quantitation (<3.0 IU/dl) was imputed as 0 IU/dl. Whiskers represent the minimum and maximum values; boxes represent the 25th and 75th percentiles. Diamonds represent the mean, and horizontal bars represent the median. CSA, chromogenic substrate assay; FVIII, factor VIII; OSA, one‐stage assay