Table 1.
Baseline characteristics
| Characteristic | Participants |
| N = 6 | |
| Male, n (%) | 5 (83) |
| Age at first screening, years, range | 6.1–12.6 |
| Age at SMA symptom onset, months, range | 8–36 |
| Age at SMA diagnosis, months, range | 9–139 |
| SMN2 gene copies, n (%) | |
| 3 | 3 (50) |
| 4 | 3 (50) |
| Motor milestones ever achieved, n (%) | |
| Sitting without support | 6 (100) |
| Standing without support | 5 (83) |
| Walking with support | 5 (83) |
| Walking without supporta | 5 (83) |
| Motor milestones at screening, n (%) | |
| Sitting without support | 6 (100) |
| Standing without support | 3 (50) |
| Walking with support | 3 (50) |
| Walking without supportb | 3 (50) |
| Wheelchair use at screening, n (%) | 4 (67) |
| Baseline HFMSE score,c range | 6–63 |
| Baseline RULM score,d range | 7–37 |
aBased on achieving walking 15 feet without support. bBased on walking 15 feet without support and achieving WHO milestone of walking (5 steps). The same three participants achieved these motor milestones at screening. cMaximum score possible on the scale: 66. dMaximum score possible on the scale: 37. HFMSE, Hammersmith Functional Motor Scale –Expanded. RULM, Revised Upper Limb Module. SMA, spinal muscular atrophy. SMN2, survival motor neuron 2.