Variable | n* | All SMA | SMA2 | SMA3 ‘sitters’ | SMA3 ‘walkers’ | ||||
Age at onset (years) | 116 | 3 (0–17) | 13 | 0.8 (0.5–12) | 51 | 3 (0.3–15) | 52 | 8 (0–17) | |
Age at T0 (years) | 116 | 34 (18–72) | 13 | 24 (19–41) | 51 | 40 (18–72) | 52 | 33 (18–68) | |
Disease duration at T0 (years) | 116 | 29 (3–63) | 13 | 22.5 (7–40.5) | 51 | 37 (14–63) | 52 | 26 (3–51) | |
Gender (F/M) | 116 | 48/68 | 13 | 3/10 | 51 | 15/36 | 52 | 30/22 | |
SMN2 copies† | Two copies | 116 | 5 (4.3%) | 13 | 3 (23.1%) | 51 | 2 (3.9%) | 52 | 0 (0%) |
Three copies | 36 (31.0%) | 6 (46.2%) | 16 (31.4%) | 14 (26.9%) | |||||
Four copies | 54 (46.6%) | 2 (15.4%) | 21 (41.2%) | 31 (59.6%) | |||||
Unknown | 21 (18.1%) | 2 (15.4%) | 12 (23.5%) | 7 (13.5%) | |||||
Salbutamol (%) | 116 | 27 (23.3%) | 13 | 5 (38.5%) | 51 | 9 (17.8%) | 52 | 13 (25.0%) | |
Ventilatory support at T0 (%) | 116 | 21 (18.1%) | 13 | 10 (76.9%)‡ | 51 | 8 (15.7%)§ | 52 | 3 (5.8%) | |
Surgery for scoliosis (%) | 116 | 16 (13.8%) | 13 | 8 (61.5%) | 51 | 7 (13.7%) | 52 | 1 (1.9%)¶ | |
Clinical assessments | |||||||||
HFMSE score | 116 | 22.5 (0–64) | 13 | 0 (0–9) | 51 | 9 (0–40) | 52 | 50.5 (17–64) | |
RULM score | 114 | 29 (0–37) | 12 | 2.5 (0–22) | 51 | 20 (0–34) | 51 | 37 (25–37) | |
6MWT (m) | NA | NA | 0 | NA | 0 | NA | 48 | 322 (14–588) | |
Rise from floor (s–1) | NA | NA | 0 | NA | 0 | NA | 28 | 0.1 (0.01–0.33) | |
Rise from chair (s–1) | NA | NA | 0 | NA | 0 | NA | 31 | 0.25 (0.06–1) | |
Climb four steps (steps/s) | NA | NA | 0 | NA | 0 | NA | 35 | 0.8 (0.17–2) | |
Run/walk 10 m (m/s) | NA | NA | 0 | NA | 0 | NA | 40 | 1.12 (0.09–2.08) | |
FVC (% of predicted) | 86 | 88.5 (11–139) | 7 | 20 (11–74) | 40 | 83 (30–128) | 39 | 102 (40–139) | |
FEV1 (% of predicted) | 76 | 92.5 (16–134) | 5 | 20 (16–55) | 35 | 84.3 (35–120) | 36 | 103 (47–134) |
Summary values are presented as median (minimum–maximum). All patients carried homozygous SMN1 exon 7 deletions, except 3: one with a nonsense and two with a missense mutation on the other allele.
*HFMSE was available for all patients, remaining assessments were not available for all patients.
†SMN2 copy number was not available in 21 patients.
‡A further patient stopped ventilatory support before T0 due to poor tolerance.
§2 patients used ventilatory support due to obstructive sleep apnea and a further patient refused ventilatory support although indicated.
¶Patient able to walk for few steps with cane.
F, female; FEV1, forced expired volume in 1 s; FVC, forced vital capacity; HFMSE, Hammersmith Functional Motor Scale Expanded; M, male; 6MWT, 6 min walk test; NA, not available; RULM, Revised Upper Limb Module; SMA, spinal muscular atrophy; SMN2, survival motor neuron 2 gene.