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Disease Profile

Spinocerebellar ataxia 15

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)

SCA15; Spinocerebellar ataxia type 15; SCA16 (formerly);


Congenital and Genetic Diseases; Nervous System Diseases


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]


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]

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:
30%-79% of people have these symptoms
Cerebellar atrophy
Degeneration of cerebellum
Gait ataxia
Inability to coordinate movements when walking
Head tremor
Increased reflexes
Upper limb postural tremor
Percent of people who have these symptoms is not available through HPO
Adult onset
Symptoms begin in adulthood
Autosomal dominant inheritance
Difficulty articulating speech
Dysmetric saccades
Uncoordinated eye movement
Gaze-evoked horizontal nystagmus
Impaired smooth pursuit
Juvenile onset
Signs and symptoms begin before 15 years of age
Limb ataxia
Postural tremor
Scanning speech
Explosive speech
Slow progression
Signs and symptoms worsen slowly with time
Truncal ataxia
Instability or lack of coordination of central trunk muscles


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.


    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 15. Click on the link to view a sample search on this topic.


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

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