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Disease Profile

Spinocerebellar ataxia 21

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 / 1 000 000

< 331

US Estimated

< 514

Europe Estimated

Age of onset

Adolescent

ICD-10

G11.1

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)

SCA21; Spinocerebellar ataxia type 21

Categories

Congenital and Genetic Diseases; Nervous System Diseases

Summary

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

Orpha Number: 98773

Definition
Spinocerebellar ataxia type 21 (SCA21) is a very rare subtype of type I autosomal dominant cerebellar ataxia (ADCA type I; see this term). It is characterized by slowly progressive cerebellar ataxia, mild cognitive impairment, postural and/or resting tremor, bradykinesia, and rigidity.

Epidemiology
Prevalence is unknown. Fewer than 20 cases in a 4-generation French family have been reported to date.

Clinical description
Mean age of onset is 17.4 years and is relatively early compared to most type I ADCAs. Individuals in successive generations tend to have earlier ages of onset. Parkinsonism was not responsive to L-dopa and magnetic resonance imaging (MRI) revealed cerebellar and brainstem atrophy.

Etiology
SCA21 maps to chromosome 7p21.3-p15.1 but the gene and gene mutation have not been identified.

Prognosis
There is insufficient clinical data to draw conclusions concerning prognosis.

Visit the Orphanet disease page for more resources.

Symptoms

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
Abnormality of extrapyramidal motor function
0002071
Gait ataxia
Inability to coordinate movements when walking
0002066
Intermittent microsaccadic pursuits
0007944
Progressive cerebellar ataxia
0002073
30%-79% of people have these symptoms
Akinesia
0002304
Behavioral abnormality
Behavioral changes
Behavioral disorders
Behavioral disturbances
Behavioral problems
Behavioral/psychiatric abnormalities
Behavioural/Psychiatric abnormality
Psychiatric disorders
Psychiatric disturbances

[ more ]

0000708
Cerebellar vermis atrophy
0006855
Cognitive impairment
Abnormality of cognition
Cognitive abnormality
Cognitive defects
Cognitive deficits
Intellectual impairment
Mental impairment

[ more ]

0100543
Dysarthria
Difficulty articulating speech
0001260
Dysgraphia
0010526
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific
Mental-retardation

[ more ]

0001249
Nystagmus
Involuntary, rapid, rhythmic eye movements
0000639
Rigidity
Muscle rigidity
0002063
Tremor
0001337
5%-29% of people have these symptoms
Diplopia
Double vision
0000651
Percent of people who have these symptoms is not available through HPO
Aggressive behavior
Aggression
Aggressive behaviour
Aggressiveness

[ more ]

0000718
Apathy
Lack of feeling, emotion, interest
0000741
Autosomal dominant inheritance
0000006
Cerebellar atrophy
Degeneration of cerebellum
0001272
Cogwheel rigidity
0002396
Global developmental delay
0001263
Hyporeflexia
Decreased reflex response
Decreased reflexes

[ more ]

0001265
Impulsivity
Impulsive
0100710
Limb ataxia
0002070
Microsaccadic pursuit
0007792
Parkinsonism
0001300
Postural tremor
0002174
Scanning speech
Explosive speech
0002168
Slow progression
Signs and symptoms worsen slowly with time
0003677
Slow saccadic eye movements
Slow eye movements
0000514

Diagnosis

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

    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

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