National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Spinocerebellar ataxia

Spinocerebellar ataxia (SCA) is a term referring to a group of hereditary ataxias that are characterized by degenerative changes in the part of the brain related to the movement control (cerebellum), and sometimes in the spinal cord.[1] There are many different types of SCA, and they are classified according to the mutated (altered) gene responsible for the specific type of SCA. The types are described using "SCA" followed by a number, according to their order of identification: SCA1 through SCA40 (and the number continues to grow). The signs and symptoms may vary by type but are similar, and may include an uncoordinated walk (gait), poor hand-eye coordination, and abnormal speech (dysarthria).[2][3] SCA is inherited in an autosomal dominant manner. However, the term "spinocerebellar" may be found with other diseases, such as the autosomal recessive spinocerebellar ataxias (SCAR).[4] Treatment is supportive and based on the signs and symptoms present in the person with SCA.[3]
Last updated: 1/19/2017
There are many different types of spinocerebellar ataxia (SCA) and each may have unique signs and symptoms. However, in general, it is difficult to differentiate among the different types, and all are characterized by problems with movement that tend to get worse over time. Affected people may experience the following:[2][3]
  • Problems with coordination and balance (ataxia)
  • Uncoordinated walk
  • Poor hand-eye coordination
  • Abnormal speech (dysarthria)
  • Involuntary eye movement
  • Vision problems
  • Difficulty processing, learning, and remembering information

Depending on the type of SCA, signs and symptoms can develop anytime from childhood to late adulthood.[3] SCA3, also known as Machado-Joseph disease, is the most common type of SCA. SCA types 9 through 36 are rare and less well characterized.[2]

Online Mendelian Inheritance in Man (OMIM), an online catalog of human genes and genetic disorders has an updated list of the SCAs subtypes.

Other diseases, not included in that classification, use the term "spinocerebellar", and have an autosomal recessive inheritance:[5]

Last updated: 1/19/2017
Mutations in many different genes are known to cause the different types of spinocerebellar ataxia (SCA). For some types, the gene known to cause it has been identified, while in others, the genetic cause is still unknown (about 40% to 25% of the cases).[3]

Some types of SCA inherited in an autosomal dominant manner are caused by trinucleotide repeat expansions.[3] A trinucleotide repeat is a segment of DNA that is repeated a number of times. It is normal for these repeats to exist and they typically do not cause any problems. However, a greater than normal number of repeats can interfere with the function of the gene, resulting in a genetic condition. Trinucleotide repeats are unstable and can change in length when passed from parent to child. An increased number of repeats often leads to an earlier age of onset and more severe disease.
Last updated: 1/19/2017
Spinocerebellar ataxia can be inherited in an autosomal dominant fashion.[1]

In autosomal dominant conditions, one mutated copy of the responsible gene in each cell is enough to cause signs or symptoms of the condition. When a person with an autosomal dominant condition has children, each child has a 50% (1 in 2) risk to inherit the mutated copy of the gene from the affected parent.

Last updated: 1/19/2017
Genetic testing is available for many different genes known to cause spinocerebellar ataxia (SCA).[3] Carrier testing for at-risk relatives and prenatal testing are possible if the disease-causing mutations in the family are known.

For some types of SCA, the genetic cause is still unknown.[3] Genetic testing is not available for families with these types of SCA.

The Genetic Testing Registry (GTR) is a centralized online resource for information about genetic tests. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional. Please see a list of laboratories offering the genetic test for SCA.               
Last updated: 1/19/2017

A diagnosis of spinocerebellar ataxia (SCA) is often suspected when certain signs and symptoms, such as a poorly coordinated gait (walk) and uncoordinated hand/finger movements, are present. Genetic testing is the best way to confirm SCA and identify the specific type, especially when a person also has family members with similar features. However, this is only an option if the disease-causing gene for that particular type of SCA has been identified. At this time, the genetic cause of some of the types is currently unknown; in these cases, imaging studies such as computed tomography (CT scan) and/or magnetic resonance imaging (MRI scan) may be necessary to establish a diagnosis. A CT scan is an imaging method that uses x-rays to create pictures of cross-sections of the body, while an MRI scan uses powerful magnets and radio waves to create pictures of the brain and surrounding nerve tissues. Both of these imaging methods can be used to identify brain abnormalities found in people with SCA.[2][3]
Last updated: 1/19/2017

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.
There is no known cure for spinocerebellar ataxia (SCA). The best treatment options for SCA vary by type and often depend on the signs and symptoms present in each person. The most common symptom of SCA is ataxia (a condition in which coordination and balance are affected). Physical therapy can help strengthen muscles, while special devices (e.g., cane, crutches, walker, or wheelchair) can assist in mobility and other activities of daily life.[1] Many people with SCA have other symptoms in addition to the ataxia such as tremors, stiffness, muscle spasms, and sleep disorders; medications or other therapies may be suggested for some of these symptoms.[3] One report described some improvement in the symptoms with zolpidem 10 mg in four out of five family members with SCA type 2, and a trial of 20 patients with SCA3 found that varenicline led to improvement in some, but not all of the symptoms.[6]
Last updated: 1/19/2017
The long-term outlook (prognosis) for people with spinocerebellar ataxia (SCA) varies. Disease progression and severity often depend on the type of SCA.[1]

Most available information on the prognosis of SCA is based on the four most common types: SCA1, SCA2, SCA3 and SCA6. People affected by one of these types of SCA usually require a wheelchair by 10-15 years after the onset of symptoms. Many will eventually need assistance to perform daily tasks.[2]
Last updated: 1/19/2017

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

  • The National Ataxia Foundation, a nonprofit organization dedicated to improving the lives of persons affected by ataxia, provides lists of neurologists, ataxia clinics, and movement disorder clinics.

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Spinocerebellar ataxia. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Patient Registry

  • Coordination of Rare Diseases at Sanford (CoRDS) hosts a specific registry for patients with ataxia in partnership with the National Ataxia Foundation. The goal of the CoRDS registry is to connect as many patients and researchers as possible to help advance treatments and cures for rare diseases. The CoRDS registry is free for patients to enroll and for researchers to access.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.

Financial Resources

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

In-Depth Information

  • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
  • 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.
  • The Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Spinocerebellar ataxia. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know.

  1. Ataxias and Cerebellar or Spinocerebellar Degeneration Information Page. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/Disorders/All-Disorders/Ataxias-and-Cerebellar-or-Spinocerebellar-Degeneration-Information-Page.
  2. Opal P & Zoghbi, HY. The Spinocerebellar Ataxias. UpToDate. 2016; http://www.uptodate.com/contents/the-spinocerebellar-ataxias.
  3. Autosomal Dominant Hereditary Ataxia. NORD. April 2014; http://rarediseases.org/rare-disease-information/rare-diseases/byID/674/viewFullReport.
  4. Bird TD. Hereditary Ataxia Overview. GeneReviews. November 26, 2014; http://www.ncbi.nlm.nih.gov/books/NBK1138/. Accessed 2/17/2015.
  5. Bird TD. Hereditary Ataxia Overview. GeneReviews; March 3, 2016; http://www.ncbi.nlm.nih.gov/books/NBK1138/.
  6. Opal P & Zoghbi HY. The Spinocerebellar Ataxias. UpToDate. July, 2016;