WHAT IS SPINAL MUSCULAR ATROPHY (SMA)?

About SMA

Spinal muscular atrophy (SMA) is a genetic disorder that starts in the central nervous system (CNS) and affects all the muscles in the body. Due to the degenerative nature of the disease, people with SMA will experience a decline in muscle strength over time, although the rate and severity can vary among individuals.

SMA is caused by a lack of spinal motor neuron (SMN) protein, a protein that’s key for muscle development and movement.

Muscles need signals from the CNS

Motor neurons send signals to muscles from the CNS. These neurons need SMN protein in order to work. Without SMN protein, motor neurons die off. With no signals from the CNS, muscles get weaker and weaker.

SMN1 is mutated in SMA

People with SMA can’t generate enough SMN protein because the survival motor neuron 1 (SMN1) gene is mutated or deleted.

SMA=insufficient SMN protein

People with SMA rely on another gene everyone has, SMN2, to make SMN protein. But this gene can’t make enough full-length protein for all the motor neurons.

People with SMA will lose motor function throughout their lives.

The rate of disease progression varies from person to person, and there is no sure way to tell when someone with SMA will start to lose motor function.

Motor function loss can become more obvious over time.

It can be hard to notice motor function loss with annual checkups because it may be happening slowly. But that doesn’t mean it isn’t happening. Such loss becomes more obvious as it continues over time.

Type and age aren’t true predictors of motor function loss.

Because everyone experiences SMA differently, there is no way to predict when motor function loss will happen or even who will experience it.

Motor function loss progresses over time. That’s why it’s important to receive an accurate diagnosis and speak with a doctor about treatment for SMA.

Genetic testing can confirm an SMA diagnosis or SMA carrier status.

Genetic testing is an important first step in accurately diagnosing rare diseases like SMA. In cases where a family history of SMA exists or symptoms suggestive of the disease present themselves, genetic testing can help to confirm the diagnosis by looking at genetic material to determine if the SMN1 gene is missing or damaged.  Some states also have newborn screening for SMA to help identify and plan for treatment before symptoms even develop. Above and beyond this, genetic testing is often required to initiate SMA treatment.

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