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Disease Profile

Spinocerebellar ataxia

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)



Nervous System Diseases


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]


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]


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.


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.

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]

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]


    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

      Learn more

      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.


          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; https://www.uptodate.com/contents/the-spinocerebellar-ataxias.
          3. Autosomal Dominant Hereditary Ataxia. NORD. April 2014; https://rarediseases.org/rare-disease-information/rare-diseases/byID/674/viewFullReport.
          4. Bird TD. Hereditary Ataxia Overview. GeneReviews. November 26, 2014; https://www.ncbi.nlm.nih.gov/books/NBK1138/. Accessed 2/17/2015.
          5. Bird TD. Hereditary Ataxia Overview. GeneReviews; March 3, 2016; https://www.ncbi.nlm.nih.gov/books/NBK1138/.
          6. Opal P & Zoghbi HY. The Spinocerebellar Ataxias. UpToDate. July, 2016;

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