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Disease Profile

Spinocerebellar ataxia 2

Prevalence
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.
1-9 / 100 000

3,310 - 29,790

US Estimated

1-9 / 100 000

5,135 - 46,215

Europe Estimated

Age of onset

All ages

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ICD-10

G11.2

Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease

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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

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X-linked
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.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder

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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.

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Not applicable

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Other names (AKA)

SCA 2; Spinocerebellar ataxia type 2; Spinocerebellar atrophy 2;

Categories

Congenital and Genetic Diseases; Nervous System Diseases

Summary

Spinocerebellar ataxia 2 (SCA2) is a progressive disorder that causes symptoms including uncoordinated movement (ataxia), speech and swallowing difficulties, muscle wasting, slow eye movement, and sometimes dementia. Signs and symptoms usually begin in mid-adulthood but can appear any time from childhood to late-adulthood. SCA2 is caused by mutations in the ATXN2 gene and is inherited in an autosomal dominant manner.[1][2]

Symptoms

Early symptoms of spinocerebellar ataxia may include uncoordinated movement (ataxia) and leg cramps. Other symptoms may include tremor; decreased muscle tone; poor tendon reflexes; abnormal eye movements; dementiadystonia and/or chorea; muscle twitches; nerve irritation and swelling (polyneuropathy); leg weakness; difficulty swallowing; bladder dysfunction; and parkinsonism.[1][2]

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:
HPO ID
80%-99% of people have these symptoms
Abnormal substantia nigra morphology
0045007
Progressive cerebellar ataxia
0002073
30%-79% of people have these symptoms
Abnormal cell morphology
0025461
Abnormality of the spinocerebellar tracts
0003133
Cerebellar Purkinje layer atrophy
0012082
Chorea
0002072
Dementia
Dementia, progressive
Progressive dementia

[ more ]

0000726
Dysarthria
Difficulty articulating speech
0001260
Dystonia
0001332
Fasciculations
Muscle twitch
0002380
Gait ataxia
Inability to coordinate movements when walking
0002066
Generalized hypotonia
Decreased muscle tone
Low muscle tone

[ more ]

0001290
Hyporeflexia
Decreased reflex response
Decreased reflexes

[ more ]

0001265
Kinetic tremor
0030186
Muscle spasm
0003394
Nystagmus
Involuntary, rapid, rhythmic eye movements
0000639
Olivopontocerebellar hypoplasia
0006955
Postural tremor
0002174
Slow saccadic eye movements
Slow eye movements
0000514
Spinal cord posterior columns myelin loss
0008311
Supranuclear ophthalmoplegia
0000623
5%-29% of people have these symptoms
Abnormal cortical gyration
0002536
Cerebral cortical atrophy
Decrease in size of the outer layer of the brain due to loss of brain cells
0002120
Cerebral white matter atrophy
0012762
Hyperactive deep tendon reflexes
0006801
Parkinsonism
0001300
Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance
0000006
Bradykinesia
Slow movements
Slowness of movements

[ more ]

0002067
Dilated fourth ventricle
0002198
Distal amyotrophy
Distal muscle wasting
0003693
Dysdiadochokinesis
Difficulty performing quick and alternating movements
0002075
Dysmetria
Lack of coordination of movement
0001310
Dysmetric saccades
Uncoordinated eye movement
0000641
Dysphagia
Poor swallowing
Swallowing difficulties
Swallowing difficulty

[ more ]

0002015
Gaze-evoked nystagmus
0000640
Genetic anticipation
0003743
Impaired horizontal smooth pursuit
0001151
Impaired vibratory sensation
Decreased vibration sense
Decreased vibratory sense
Diminished vibratory sense
Impaired vibratory sense

[ more ]

0002495
Limb ataxia
0002070
Muscular hypotonia
Low or weak muscle tone
0001252
Myoclonus
0001336
Oculomotor apraxia
0000657
Olivopontocerebellar atrophy
0002542
Ophthalmoplegia
Eye muscle paralysis
0000602
Postural instability
Balance impairment
0002172
Rigidity
Muscle rigidity
0002063
Rod-cone dystrophy
0000510
Spasticity
Involuntary muscle stiffness, contraction, or spasm
0001257
Spinocerebellar tract degeneration
0002503
Urinary bladder sphincter dysfunction
0002839

Diagnosis

Molecular genetic testing (analysis of DNA) is needed for a diagnosis of spinocerebellar ataxia 2 (SCA2). This testing detects abnormal CAG trinucleotide repeat expansions in the ATXN2 gene. Affected people (or people who will later develop symptoms of SCA2) have a copy of the ATXN2 gene that has 33 or more CAG repeats. This testing detects nearly 100% of cases of SCA2.[1]

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.
  • Orphanet lists international laboratories offering diagnostic testing for this condition.
  • 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.

    Treatment

    Treatment of spinocerebellar ataxia 2 (SCA2) is supportive and aims to help the affected person maintain their independence and avoid injury. It is recommended that people with SCA2 remain physically active, maintain a healthy weight, use adaptive equipment as needed, and avoid alcohol and medications that affect cerebellar function. Adaptive equipment may include canes or other devices to help with walking and mobility. People with SCA2 may develop difficulty speaking and may need to use computerized devices or writing pads to help with communication. Levodopa may be prescribed to help with some of the movement problems (e.g., rigidity and tremor), and magnesium may improve muscle cramping.[1][3][4]

    Organizations

    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.
        • MeSH® (Medical Subject Headings) is a terminology tool used by the National Library of Medicine. Click on the link to view information on this topic.
        • 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.
        • The Neuromuscular Disease Center at Washington University provides information about spinocerebellar ataxia 2.
        • 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 2. Click on the link to view a sample search on this topic.

          References

          1. Pulst SM. Spinocerebellar ataxia type 2. GeneReviews. November 12, 2015; https://www.ncbi.nlm.nih.gov/books/NBK1275/.
          2. Spinocerebellar ataxia type 2. Genetics Home Reference. February, 2011; https://ghr.nlm.nih.gov/condition/spinocerebellar-ataxia-type-2.
          3. Lastres-Becker I, Rüb U, Auburger G. Spinocerebellar ataxia 2 (SCA2). Cerebellum. 2008;
          4. Spinocerebellar degenerations. Neuromuscular Disease Center at Washington University. 2009; https://neuromuscular.wustl.edu/ataxia/domatax.html#sca2.

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