What is Spinal Muscular Atrophy (SMA)? As we’ve previously
discussed, children with type 1 SMA never sit, children with
type 2 SMA never walk independently, however children with type
3 and type 4 SMA achieve independent ambulation. They are able
to walk without assistance, at least for some time in their
lives. Children with type 3 SMA are oftentimes arbitrarily
categorized as having type 3-a or type 3-b SMA. In children with
type 3-a SMA, there are usually symptoms present of weakness or
decreased endurance before the age of 3. And typically, the
child with type 3-b is perfectly normal for the first three
years of life. Is it important to make this distinction?
Perhaps, in that, prolonged independent ambulation for years or
even decades is far more common if a child is a-symptomatic
until the age of 3. The variability of clinical presentation and
disease progression in children with type 3 SMA and young or
midlife adults with type 4 SMA makes a “one treatment plan fits
all” impossible, and I believe that th