Table 2 Historical spinal muscular atrophy subtypes [10, 19]
From: Advances and limitations for the treatment of spinal muscular atrophy
Type | Onset | Symptoms | Milestones |
|---|---|---|---|
0 | Prenatal | Respiratory failure at birth | Â |
1 | 0–6 months | Severe deficits in motor function. Difficulties in breathing, coughing, and swallowing, fasciculations of the tongue | No sitting |
2 |  < 18 months | Severe deficits in motor function. Delay in motor development, weakness, difficulties in coughing, joint contractures, scoliosis | Sitting, no walking |
3 |  > 18 months | Variable degree of weakness, joint contractures, scoliosis, loss of ambulation | Independent walking |
4 | 30Â years | Variable, but milder weakness | Independent walking |