About spinal muscular atrophy (SMA)/What is SMA

For patients with SMA, disease progression is lifelong.^1-3

SMA is a progressive neuromuscular disease.⁴

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, although the rate and severity vary. Watch to learn more about the cause and symptoms of SMA.^3-5

Mechanism of disease

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

The broad range of SMA symptoms includes⁶ :

// 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

“My entire life has been one slow, physical decline—a race against time.
And before I was officially diagnosed with SMA, neither I nor my family knew why.”

—Bill, diagnosed with later-onset SMA

SMA is caused by a lack of functional SMN protein.⁴

Two nearly identical genes produce survival motor neuron (SMN) protein.⁷

the importance of SMN1 gene and the SMN2 gene for producing functional SMN protein.

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

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

Motor function loss is permanent and can be unpredictable.^1,5,8

Because the rate of motor function loss is different for every patient, there is no way to predict when motor function loss will occur or how severe it will be.