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How does Evrysdi work for SMA?

Medically reviewed by Carmen Pope, BPharm. Last updated on June 1, 2022.

Official answer


Evrysdi (risdiplam) works by targeting the SMN2 gene (survival motor neuron gene 2), causing it to make more functional SMN protein. This increases SMN protein levels throughout the central nervous system and body, helping to improve motor nerve and muscle function in children and adults with spinal muscular atrophy (SMA).

Evrysdi must be taken for a person's lifetime.

Evrysdi was approved by the FDA on August 7, 2020 and is available as a liquid that is given by mouth or through a gastrostomy tube (g-tube) once a day after a meal. It may be used to treat all types of SMA in adults, children, and newborns. A label extension for Evrysdi in May, 2022 to include pre-symptomatic infants aged under 2 months (or newborns) allows healthcare providers to intervene as early as possible in treating babies with SMA.

What is spinal muscular atrophy (SMA)?

SMA is a rare genetic disease that is caused by a mutation in the survival motor neuron gene 1 (SMN1). This gene produces a protein that is critical to the function of the nerves that control our muscles. Without this protein, motor nerve cells die, muscles become progressively weaker and waste away (atrophy), leaving children and adults unable to properly eat or breathe and robbing them of their physical strength and their ability to walk. However, it does not affect a person’s ability to think, learn, and build relationships with others. SMA is the number one genetic cause of death for infants, with many dying at a young age from respiratory failure.

All children and adults with SMA have at least one “backup gene,” known as SMN2. This gene has a similar structure to SMN1, but only around 10% of the SMN protein it produces is fully functional.

SMA can affect any race or gender and about 1 in every 50 Americans is a genetic carrier. SMA affects approximately 1 in 11,000 births and there are four primary types of SMA: 1, 2, 3, and 4.


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