Rare Neurology News

Disease Profile

Spinocerebellar ataxia 5

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.

<1 / 1 000 000

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)

SCA5; Spinocerebellar ataxia type 5


Congenital and Genetic Diseases; Nervous System Diseases


Spinocerebellar ataxia 5 (SCA5) is one of the many spinocerebellar ataxias, which are inherited conditions that cause degeneration of the spinal cord and cerebellum. SCA5 almost exclusively affects the cerebellum. It is considered to be a mild form that progresses slowly. The age of onset is usually between the ages of 20 and 30, but a wide range in age of onset has been reported.[1] Signs and symptoms may include loss of coordination of the hands, arms, and legs; impaired balance when walking; and slurred speech (dysarthria).[2] SCA5 is caused by mutations in the SPTBN2 gene and is inherited in an autosomal dominant manner.[3]


Unlike some other forms of spinocerebellar ataxia, SCA5 almost exclusively affects the cerebellum.[1][2] It is generally a slowly progressive condition. Symptoms often begin in a person's 20s, but age of onset between infancy and 68 years has been reported. Signs and symptoms usually include:[2][4]

  • ataxia (loss of coordination) of the hands, arms, legs, and gait
  • slurred speech (dysarthria) usually not severe and doesn't interfere with spoken communication
  • ocular (eye) problems such as nystagmus

All known affected individuals have remained ambulatory despite having the condition for several decades. Non-cerebellar symptoms occur rarely but have included facial myokymia (spontaneous, fine muscle contractions); limited lateral gaze; tremor; writer's cramp; brisk reflexes; and impaired vibration.[3][4]

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Cerebellar atrophy
Degeneration of cerebellum
Gait disturbance
Abnormal gait
Abnormal walk
Impaired gait

[ more ]

Difficulties in coordination
Incoordination of limb movements
Limb incoordination

[ more ]

Slurred speech
5%-29% of people have these symptoms
Generalized hypotonia
Decreased muscle tone
Low muscle tone

[ more ]

Global developmental delay
Infantile onset
Onset in first year of life
Onset in infancy

[ more ]

Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance
Cognitive impairment
Abnormality of cognition
Cognitive abnormality
Cognitive defects
Cognitive deficits
Intellectual impairment
Mental impairment

[ more ]

Difficulty articulating speech
Difficulty performing quick and alternating movements
Lack of coordination of movement
Facial myokymia
Involuntary facial quivering
Gait ataxia
Inability to coordinate movements when walking
Gaze-evoked nystagmus
Increased reflexes
Impaired smooth pursuit
Impaired vibratory sensation
Decreased vibration sense
Decreased vibratory sense
Diminished vibratory sense
Impaired vibratory sense

[ more ]

Intention tremor
Limb ataxia
Age symptoms begin
Slow progression
Signs and symptoms worsen slowly with time
Upper motor neuron dysfunction


Once a hereditary ataxia is considered in a person, several factors are involved in finding the specific type of ataxia present. These include the person's medical history, a physical examination, a neurologic examination, neuroimaging, a detailed family history, and molecular genetic testing.[5] In a person with ataxia and a family history consistent with autosomal dominant inheritance, it is hard to find the exact diagnosis without genetic testing. This is because there is so much overlap of symptoms between all the forms of hereditary ataxia.[5]

Most labs that test for hereditary ataxias have a panel of tests that include testing for the forms that are most common and are known to be associated with specific genes and mutations. These forms may include SCA1, SCA2, SCA3, SCA6, SCA7, SCA10, SCA12, SCA14, and SCA17 (these are all associated with a specific type of mutation called a repeat expansion). Many labs offer them as groups in a step-wise fashion based on how commonly they occur. Testing can also be done for other autosomal dominant forms that are not associated with repeat expansions, including SCA5.[5] If a specific type of SCA is already known to occur in a family member based on genetic testing, a person can have testing only for that specific type of SCA.

It is important to note that genetic testing may not always give a clear diagnosis, because genetic testing is not yet available for all hereditary ataxias. If a person who clearly has a hereditary ataxia has a normal genetic test result, they might have a type of SCA for which testing is not available.[6]

People who have questions about a diagnosis of SCA and genetic testing for themselves or family members should speak with a neurologist and/or a genetics professional.

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.
  • Spinocerebellar Ataxia: Making an Informed Choice about Genetic Testing is a booklet providing information about spinocerebellar ataxia and is available as a PDF document on the University of Washington Medical Center Web site. Click on the title above to view this resource.


    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.
        • 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. 
        • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
        • PubMed is a searchable database of medical literature and lists journal articles that discuss Spinocerebellar ataxia 5. Click on the link to view a sample search on this topic.


          1. Puneet Opal and Huda Y Zoghbi. The spinocerebellar ataxias. UpToDate. Waltham, MA: UpToDate; June, 2014; Accessed 6/13/2014.
          2. Spinocerebellar Ataxia Type 5 (SCA5). National Ataxia Foundation. September, 2004; https://www.ataxia.org/pdf/sca5.pdf. Accessed 6/16/2014.
          3. Cassandra L. Kniffin. SPINOCEREBELLAR ATAXIA 5; SCA5. OMIM. August 28, 2013; https://omim.org/entry/600224. Accessed 6/16/2014.
          4. Jacob FD, Ho ES, Martinez-Ojeda M, Darras BT, Khwaja OS. Case of infantile onset spinocerebellar ataxia type 5. J Child Neurol. October, 2013; 28(10):1292-5. Accessed 6/16/2014.
          5. Thomas D Bird. Hereditary Ataxia Overview. GeneReviews. 2016; https://www.ncbi.nlm.nih.gov/books/NBK1138/.
          6. Corrine O’Sullivan Smith, Sara J. Michelson, Robin L. Bennett, Thomas D. Bird. Spinocerebellar Ataxia: Making an Informed Choice About Genetic Testing. University of Washington Medical Center. November, 2004; https://depts.washington.edu/neurolog/images/neurogenetics/ataxia.pdf. Accessed 6/16/2014.

          Rare Neurology News