-BMD cohort results:Low dose (3 × 1011 vg/kg/leg): +58 m and +125 m in 6MWTHigh dose (6 × 1011 vg/kg/leg): +108 m and +29 m in 6MWTHistology: Decreased fibrosis, increased central nuclei, muscle fiber hypertrophyNo gene transfer-related adverse events-DMD cohort:Primary endpoint: SafetySecondary endpoints: 6MWT, imaging, histology, immune monitoring, quality of lifeResults pending-Follistatin overexpression inhibits myostatin to promote muscle growth-Increased muscle volume-Enhanced strength and functional capacity-No serious adverse events reported. Here, FST is linked to Duchenne muscular dystrophy.