RPE65 and hemophilia B: Subsequently, other serotypes such as AAV8 have demonstrated substantial clinical benefits in patients with hemophilia B.7 However, clinical observations in both the hepatic5 and ocular gene therapy trials with AAV28 have revealed that low doses of AAV2-FIX vectors (up to 4 × 1011 vector genomes [vgs]/kg) are immunologically safe but therapeutically suboptimal; while in LCA2 patients who received a low dose (1 × 1011 vgs/eye) of AAV2-RPE65 vectors, there was a negligible vision rescue.