SMA progression is continuous1-3

Spinal muscular atrophy (SMA) is a progressive neuromuscular disease4

SMA is defined as a neuromuscular disease of the central nervous system (CNS) that results in the deterioration of motor function and strength over time, due to motor neuron loss, although the rate and severity vary.3,5,6

Natural history studies of SMA show that progression is a threat across disease type.2

Watch to learn more about the causes and symptoms of SMA.

Mechanism of disease

Watch the video to learn about the clinical manifestations and cause of SMA.

The broad range of SMA symptoms includes7:

  • Weakness that is usually symmetrical and more proximal than distal
  • Absent or diminished tendon reflexes
  • Difficulty or inability to walk
  • Respiratory issues that may require tracheostomy or ventilation

SMA is caused by a lack of functional survival motor neuron (SMN) protein5

Two nearly identical genes produce SMN protein4

People with SMA have a homozygous deletion of their SMN1 gene, and rely on the SMN2 gene to produce functional SMN protein. However, SMN2 can only produce about 10% of the protein the motor neurons need to power muscles, resulting in the progressive loss of strength and motor function that all patients with SMA experience.4,5

Because motor function loss progresses over time, it is important that patients receive an accurate diagnosis and speak with a healthcare professional about treatment options.4

Why it’s important to consider treating SMA as soon as possible

Motor function loss may be permanent and unpredictable2,9,10

Motor neuron loss is irreversible, leading to progressive muscle weakness, motor function impairment, and disability.

SMA progression can go unnoticed for years2,9,11

For adults with later-onset SMA, it can be hard to recognize progression. Genetic testing can help accurately diagnose SMA, while continued monitoring can help measure progression.

SMA, spinal muscular atrophy; SMN, survival motor neuron; SMN1, survival motor neuron 1 gene; SMN2, survival motor neuron 2 gene.