Overview of SMA and the natural history of types 2 and 3 SMA
SMA, autosomal recessive neuromuscular disorder
SPINAL MUSCULAR ATROPHY 4
Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder caused by reduced levels of survival of motor neuron (SMN) protein due to homozygous deletions or loss-of-function mutations in the Patients with type 2 SMA develop symptoms between 6 and 18 months of age, achieve the ability to sit independently and occasionally stand or take a few steps with support, but are unable to walk independently [