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Disease Profile

Familial infantile convulsions and paroxysmal choreoathetosis

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.

Unknown

Age of onset

Infancy

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ICD-10

G40.4

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)

ICCA; Convulsions, infantile, with paroxysmal choreoathetosis, familial; ICCA syndrome

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.
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Orpha Number: 31709

Definition
Infantile Convulsions and paroxysmal ChoreoAthetosis (ICCA) syndrome is a neurological condition characterized by the occurrence of seizures during the first year of life (Benign familial infantile epilepsy ; see this term) and choreoathetotic dyskinetic attacks during childhood or adolescence.

Epidemiology
This disorder is rare but the exact prevalence is unknown.

Clinical description
Benign familial infantile epilepsy begins at 3 to 12 months of age with a family history of the same type of seizures. Seizures are afebrile, partial or sometimes generalized, and normally disappear after the first year of life. During childhood or adolescence, affected individuals present with paroxysmal kinesigenic dyskinesia with frequent and recurrent episodic choreathetotic or dystonic movements that last less than 1 minute. The attacks are triggered by the initiation of voluntary movements or startle. The association with other paroxysmal disorders such as migraine, with or without aura, hemiplegic migraine, episodic ataxia and tics has also been described. Psychomotor development is normal.

Etiology
The genetic loci of ICCA syndrome have been described on chromosomes 16p11.2-q12.1, 16q13-q22.1 and 3q29-29. Mutations in the Proline-rich transmembrane protein 2 (PRRT2) gene, located on 16p11.2, have recently been found in families affected by ICCA syndrome. This gene encodes a membrane protein that interacts with the presynaptic protein SNAP-25 but the mechanism leading to the disease remains unknown.

Diagnostic methods
The diagnosis is mainly clinical, based on the appearance of infantile convulsions with benign evolution followed by kinesigenic dyskinesia attacks later on. Genetic testing confirms the diagnosis.

Differential diagnosis
Differential diagnosis includes other paroxysmal dystonias such as paroxysmal exertion-induced dyskinesia and paroxysmal non-kinesigenic dyskinesia (see these terms) triggered by drugs or food intake (such as caffeine and alcohol).

Genetic counseling
ICCA syndrome can present as sporadic or familial; in the latter case, it is transmitted as an autosomal dominant trait that can be variably expressed within the same family.

Management and treatment
Antiepileptic drugs, mainly phenytoin or carbamazepine, are effective in controlling seizures and dyskinesia during the active phase of the disorder.

Prognosis
ICCA has a good outcome. Without treatment, dyskinetic attacks tend to disappear during adulthood.

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
Normal interictal EEG
0002372
30%-79% of people have these symptoms
Athetosis
Involuntary writhing movements in fingers, hands, toes, and feet
0002305
Choreoathetosis
0001266
Dystonia
0001332
Focal impaired awareness seizure
0002384
Paroxysmal dyskinesia
0007166
5%-29% of people have these symptoms
Complex febrile seizure
0011172
Experiential epileptic aura
0012002
Percent of people who have these symptoms is not available through HPO
Anxiety
Excessive, persistent worry and fear
0000739
Autosomal dominant inheritance
0000006
Generalized-onset seizure
0002197
Paroxysmal choreoathetosis
0007098
Paroxysmal dystonia
0002268

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.

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 Familial infantile convulsions and paroxysmal choreoathetosis. Click on the link to view a sample search on this topic.