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 20



Other Names:
SCA20; Spinocerebellar ataxia type 20
Categories:
This disease is grouped under:

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

Orpha Number: 101110

Definition
Spinocerebellar ataxia type 20 (SCA20) is a very rare subtype of type I autosomal dominant cerebellar ataxia (ADCA type I; see this term). It is characterized by cerebellar dysarthria as the initial typical manifestation.

Epidemiology
Prevalence is unknown. Fewer than 20 cases in a 4-generation Australian family of Anglo-Celtic descent have been reported to date.

Clinical description
Age of symptomatic disease onset ranges from 19 to 64 years (mean age = 46.5 years). Most affected patients also exhibit palatal tremor and spasmodic dysphonia. Head computed tomography (CT) shows dentate calcifications.

Etiology
SCA20 has been linked to chromosome 11q12.2-11q12.3, overlapping with the locus for SCA5 (see this term), though clinical features differ. SCA5 belongs to type III ADCA (see this term) and represents a pure ataxia syndrome with on average earlier age of symptomatic disease onset ranging from 14 to 50 years. Since the causative gene is unknown, SCA20 and SCA5 may be proven genetically to be the same disorder.

Prognosis
Prognosis is relatively good. Most patients can walk with or without gait aids and many patients live to more than 60 years of age.

Visit the Orphanet disease page for more resources.
Last updated: 5/1/2011

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
80%-99% of people have these symptoms
Dysarthria
Difficulty articulating speech
0001260
30%-79% of people have these symptoms
Bradykinesia
Slow movements
Slowness of movements
[ more ]
0002067
Cerebellar atrophy
Degeneration of cerebellum
0001272
Cerebral calcification
Abnormal deposits of calcium in the brain
0002514
Hypermetric saccades 0007338
Laryngeal dystonia 0012049
5%-29% of people have these symptoms
Abnormal pyramidal sign 0007256
Downbeat nystagmus 0010545
Gait ataxia
Inability to coordinate movements when walking
0002066
Gaze-evoked nystagmus 0000640
Hyperreflexia
Increased reflexes
0001347
Isometric tremor 0030185
Upper limb postural tremor 0007351
Vertigo
Dizzy spell
0002321
1%-4% of people have these symptoms
Intention tremor 0002080
Percent of people who have these symptoms is not available through HPO
Adult onset
Symptoms begin in adulthood
0003581
Autosomal dominant inheritance 0000006
Dysphonia
Inability to produce voice sounds
0001618
High pitched voice 0001620
Limb ataxia 0002070
Nystagmus
Involuntary, rapid, rhythmic eye movements
0000639
Palatal myoclonus 0010530
Postural tremor 0002174
Slow progression
Signs and symptoms worsen slowly with time
0003677
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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


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

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