Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is a genetic, progressive, and often terminal rare disease that affects an individual’s ability to walk, eat, and, ultimately, breathe. Debilitating and often fatal, SMA affects approximately one in 10,000 individuals and is the leading genetic cause of death among infants.1

SMA impacts individuals across a range of ages – from infants and children to teens and adults – with varying levels of severity. The most severe form, infantile onset SMA (also known as Type 1), affects newborns and infants and can lead to paralysis and prevent infants from performing the basic functions of life, such as swallowing or holding up their heads. Later-onset SMA (Types 2 and 3) is most common among teens and adults, who may experience significant muscle weakness and disability, such as the inability to stand or walk independently.

Spinal muscular atrophy is caused by a mutation in both copies of the survival motor neuron 1 (SMN1) gene. Loss of the SMN1 protein is partially compensated by expression of SMN2, a highly similar gene. Therefore, individuals with SMA who have two copies of the SMN2 gene, are most likely to develop infantile-onset SMA, while those with three or four copies are most likely to develop later-onset SMA.

Therapy for SMA

Previously, individuals with SMA and their families had no treatment options. This changed in December 2016 when Biogen received U.S. Food and Drug Administration (FDA) approval for a therapy to treat SMA. The therapy has since been approved in the European Union, Japan, Brazil, and other regions globally, and has helped thousands of patients around the world to date.

We continue to work with healthcare professionals, government bodies, policymakers, and advocacy groups to be able to provide access to this new therapy as quickly as possible to as many who may benefit.


1.  Mercuri et al. Nat Rev Neurol. (2020) 16(12):706–15



Biogen 122340 V2  Date of Preparation: June 2023