Human factor IX-specific APTT assay of FIXKO and R33Q-hFIX mouse with and without gene therapy
. | Average factor IX activity ± SD, % . | Range of activities, % . |
|---|---|---|
| Wild-type, untreated, C57BL/6 | 30 ± 8 | 14-45 |
| FIXKO, untreated | 0.2 ± 0.2 | 0.0-0.7 |
| R333Q-hFIX, untreated | 0.9 ± 0.9 | 0.1-3.2 |
| R333Q-hFIX, 4 mo after treatment | 6.6 ± 7.8 | 0.8 ± 19.8 |
| FIXKO, 4 mo after treatment | 0.8 ± 1.0 | 0.1-2.6 |
. | Average factor IX activity ± SD, % . | Range of activities, % . |
|---|---|---|
| Wild-type, untreated, C57BL/6 | 30 ± 8 | 14-45 |
| FIXKO, untreated | 0.2 ± 0.2 | 0.0-0.7 |
| R333Q-hFIX, untreated | 0.9 ± 0.9 | 0.1-3.2 |
| R333Q-hFIX, 4 mo after treatment | 6.6 ± 7.8 | 0.8 ± 19.8 |
| FIXKO, 4 mo after treatment | 0.8 ± 1.0 | 0.1-2.6 |
The ability of mouse samples to initiate clotting in human factor IX-deficient plasma is measured by shortening of the APTT clotting time. Clotting times from dilutions of human reference plasma are used to derive a standard curve for calculation of percent human factor IX activity. Mice treated with gene therapy were tested 4 months after intramuscular administration of rAAV2-CBA-hFIX. Populations: wild-type, untreated, C57BL/6, n = 13; FIXKO, untreated, n = 15; R333Q-hFIX, untreated, n = 14; R333Q-hFIX, 4 months after treatment, n = 6; and FIXKO, 4 months after treatment, n = 5.