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Genetic and Rare Diseases Information Center (GARD)

Spinal muscular atrophy


Spinal muscular atrophy (SMA) refers to a group of inherited conditions that affect the muscles. The severity of the condition; the associated signs and symptoms; and the age at which symptoms develop varies by subtype. In general, people with SMA experience progressive weakness and atrophy of muscles involved in mobility, the ability to sit unassisted, and head control. Breathing and swallowing may also be affected in severe cases.[1][2][3] SMA is generally caused by changes (mutations) in the SMN1 gene and is inherited in an autosomal recessive manner. Extra copies of the SMN2 gene modify the severity of SMA. Rare autosomal dominant (caused by mutations in DYNC1H1 or VAPB) and X-linked (caused by mutations in UBA1) forms of SMA exist.[4] Treatment is based on the signs and symptoms present in each person.[5][2]
Last updated: 1/7/2016


  1. Learning About Spinal Muscular Atrophy. National Human Genome Research Institute. 2012;
  2. Spinal muscular atrophy. MedlinePlus. February 2014;
  3. Spinal Muscular Atrophy. National Organization for Rare Disorders. 2012;
  4. Spinal muscular atrophy. Genetics Home Reference (GHR). January 2013;
  5. Bryan Tsao, MD. Spinal Muscular Atrophy. Medscape Reference. December 2015;
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Basic Information

  • Families of SMA has created a booklet entitled Understanding SMA that is intended to serve as a source of information and support for children and adults with Spinal Muscular Atrophy (SMA). 
  • Genetics Home Reference (GHR) contains information on Spinal muscular atrophy. This website is maintained by the National Library of Medicine.
  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
  • The National Human Genome Research Institute's (NHGRI) website has an information page on this topic. NHGRI is part of the National Institutes of Health and supports research on the structure and function of the human genome and its role in health and disease.
  • The National Institute of Neurological Disorders and Stroke (NINDS) collects and disseminates research information related to neurological disorders. Click on the link to view information on this topic.
  • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

In Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Spinal muscular atrophy. Click on the link to view a sample search on this topic.
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