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 15



Other Names:
SCA15; Spinocerebellar ataxia type 15; SCA16 (formerly); SCA15; Spinocerebellar ataxia type 15; SCA16 (formerly); Spinocerebellar ataxia 16 (formerly) See More
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Spinocerebellar ataxia 15 (SCA15) is a neurological condition characterized by slowly progressive gait and limb ataxia, often in combination with eye movement abnormalities and  balance, speech and swallowing difficulties. The onset of symptoms typically occurs between ages 7 and 66 years. The ability to walk independently is often maintained for many years following onset of symptoms. SCA15 is caused by mutations in the ITPR1 gene. It is inherited in an autosomal dominant manner. Diagnosis is based on clinical history, physical examination, molecular genetic testing, and exclusion of other similar diseases. There is no effective treatment known to modify disease progression. Patients may benefit from occupational and physical therapy for gait dysfunction and speech therapy for dysarthria.[1] 
Last updated: 1/22/2013

Spinocerebellar ataxia 15 (SCA15) is characterized by slowly progressive gait and limb ataxia, often in combination with ataxic dysarthria, titubation, upper limb postural tremor (which occurs when a person tries to maintain a position against gravity, such as holding the arms outstretched), mild hyperreflexia (exaggerated reflexes), gaze-evoked nystagmus, and impaired vestibulo-ocular reflex gain (an inability to stabilize the eyes during small head tremors, which makes it difficult to read, etc.). Mild dysphagia and movement-induced oscillopsia (a bouncing and blurring of vision) have been observed in some patients. Symptoms typically present between the ages of 7 and 66 years. Gait ataxia and tremor are often the first noticeable symptoms. The ability to walk independently may be maintained for many years (or even decades) following onset of symptoms.[1]
Last updated: 1/22/2013

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.

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Medical Terms Other Names
Learn More:
HPO ID
30%-79% of people have these symptoms
Cerebellar atrophy
Degeneration of cerebellum
0001272
Gait ataxia
Inability to coordinate movements when walking
0002066
Head tremor 0002346
Hyperreflexia
Increased reflexes
0001347
Upper limb postural tremor 0007351
Percent of people who have these symptoms is not available through HPO
Adult onset
Symptoms begin in adulthood
0003581
Autosomal dominant inheritance 0000006
Dysarthria
Difficulty articulating speech
0001260
Dysmetric saccades
Uncoordinated eye movement
0000641
Gaze-evoked horizontal nystagmus 0007979
Impaired smooth pursuit 0007772
Juvenile onset
Signs and symptoms begin before 15 years of age
0003621
Limb ataxia 0002070
Postural tremor 0002174
Scanning speech
Explosive speech
0002168
Slow progression
Signs and symptoms worsen slowly with time
0003677
Truncal ataxia
Instability or lack of coordination of central trunk muscles
0002078
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Last updated: 7/1/2020

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare 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.

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


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.

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.
  • 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 15. 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. Storey E. Spinocerebellar Ataxia Type 15. GeneReviews. April 2011; http://www.ncbi.nlm.nih.gov/books/NBK1362/. Accessed 1/22/2013.