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Disease Profile

Spinocerebellar ataxia 26

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)

SCA26; Spinocerebellar ataxia type 26


Congenital and Genetic Diseases; Nervous System Diseases


The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.

Orpha Number: 101112

A very rare subtype of autosomal dominant cerebellar ataxia type III (ADCA type III) characterized by late-onset and slowly progressive cerebellar signs (gait ataxia) and eye movement abnormalities.

To date, only 23 affected patients have been described from one American family of Norwegian descent.

Clinical description
Spinocerebellar ataxia type 26 (SCA26) onset occurs between the ages of 26-60 with a mean age of onset of 42 years. Slowly progressive gait ataxia and dysarthria were reported in all patients. Nystagmus, impaired pursuit, and dysmetric saccades were described in majority of patitents. Left-sided pyramidal signs (hyperreflexia with positive Babinski sign) were reported in one patient. The disease duration is unknown.

A candidate gene for SCA26 has recently been identified as the eukaryotic translation elongation factor 2 (EEF2) gene, located on chromosome 19p13.3. Further confirmatory studies are still required in order to determine if a mutation in this gene directly causes SCA26.

Diagnostic methods
Diagnosis is based on the clinical findings of pure cerebellar ataxia as well as molecular findings. Head magnetic resonance imaging (MRI) usually demonstrates the presence of atrophy of the cerebellum sparing the brainstem and is helpful in excluding other causes of ataxia. Molecular genetic testing identifies a mutation in the EEF2 gene, confirming a diagnosis of SCA26.

Differential diagnosis
Differential diagnoses include other forms of ADCA type III, in particular SCA5, SCA6, SCA11, SCA30 and SCA31.

Antenatal diagnosis
Antenatal diagnosis is possible in families with a known disease causing mutation.

Genetic counseling
SCA26 is inherited autosomal dominantly and genetic counseling is possible. Genetic counseling should be proposed to individuals having the disease-causing mutation informing them that there is 50% risk of passing the mutation to offspring.

Management and treatment
There is no cure for SCA26 and treatment is supportive. Neurological follow-up is recommended to monitor the progression of ataxia.

Disease progression is very slow, but precise prognosis is unknown.

Visit the Orphanet disease page for more resources.


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
Difficulty articulating speech
Impaired horizontal smooth pursuit
Limb ataxia
Progressive cerebellar ataxia
Progressive gait ataxia
30%-79% of people have these symptoms
Cerebellar atrophy
Degeneration of cerebellum
Dysmetric saccades
Uncoordinated eye movement
Involuntary, rapid, rhythmic eye movements
Truncal ataxia
Instability or lack of coordination of central trunk muscles
5%-29% of people have these symptoms
Babinski sign
Generalized hyperreflexia
Percent of people who have these symptoms is not available through HPO
Adult onset
Symptoms begin in adulthood
Autosomal dominant inheritance
Gait ataxia
Inability to coordinate movements when walking
Difficulties in coordination
Incoordination of limb movements
Limb incoordination

[ more ]

Slow progression
Signs and symptoms worsen slowly with time


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


    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

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