Children with less severe SMA can live to adulthood, although with profound physical disabilities.

Sprouting has been difficult to study in severe SMA mice due to their short lifespan.

Small molecules that modify SMN2 splicing towards increased production of functional SMN significantly ameliorate SMA phenotypes in mouse models of severe SMA.

Finally, myofibers from a mouse model of severe SMA, but not controls, display morphological defects that are consistent with a Z-disc deficiency.