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Disease Profile

KCNQ2-Related Disorders

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

#N/A

ICD-10

#N/A

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.

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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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Categories

Congenital and Genetic Diseases; Nervous System Diseases

Summary

KCNQ2-related disorders are a group of epileptic diseases that start during the first 4 weeks of a child's life (neonatal period).[1] The groups is made up of various different diseases whose signs and symptoms vary. The conditions range from the less severe form KCNQ2-related benign familial neonatal epilepsy (KCNQ2-BFNE) to the more severe form KCNQ2-related epileptic encephalopathy (KCNQ2-NEE). KCNQ2-BFNE is characterized by seizures that start in otherwise healthy infants around day 3 of life and usually go away within 1 to 4 months. KCNQ2-NEE is characterized by epilepsy and profound intellectual disability and seizures that begin in the first weeks of life and typically show little response to treatment. They usually go away in a few months to a few years but can return later in childhood.[2][1] These disorders are caused by mutations in the KCNQ2 gene. Inheritance is autosomal dominant. Treatment is with antiseizure medications.[1]

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
100% of people have these symptoms
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific
Mental-retardation

[ more ]

0001249
80%-99% of people have these symptoms
EEG with burst suppression
0010851
Epileptic encephalopathy
0200134
Generalized tonic seizure
0010818
30%-79% of people have these symptoms
Abnormal globus pallidus morphology
0002453
Apnea
0002104
Cerebral edema
Swelling of brain
0002181
Dystonia
0001332
Epileptic spasm
0011097
Facial erythema
Blushed cheeks
Blushing
Red face
Red in the face

[ more ]

0001041
Feeding difficulties
Feeding problems
Poor feeding

[ more ]

0011968
Inability to walk
0002540
Muscular hypotonia
Low or weak muscle tone
0001252
Pallor
0000980
Poor gross motor coordination
0007015
Profound global developmental delay
0012736
5%-29% of people have these symptoms
Cerebral atrophy
Degeneration of cerebrum
0002059
Febrile seizure (within the age range of 3 months to 6 years)
Fever induced seizures
0002373
Global developmental delay
0001263
Hypoplasia of the corpus callosum
Underdevelopment of part of brain called corpus callosum
0002079
Hypsarrhythmia
0002521
Motor delay
0001270
Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance
0000006
Bilateral tonic-clonic seizure
Grand mal seizures
0002069
Focal clonic seizure
0002266
Generalized hypotonia
Decreased muscle tone
Low muscle tone

[ more ]

0001290
Infantile onset
Onset in first year of life
Onset in infancy

[ more ]

0003593
Myokymia
0002411
Neonatal onset
0003623
Seizure
0001250
Spastic tetraparesis
0001285

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.

    In-Depth Information

    • 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. 
      Online Mendelian Inheritance in Man (OMIM)
      Online Mendelian Inheritance in Man (OMIM)
    • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.

      References

      1. Miceli F & cols. KCNQ2-Related Disorders. GeneReviews. March 31, 2016; https://www.ncbi.nlm.nih.gov/books/NBK32534/.
      2. KCNQ2. Genetics Home Reference. 2013; https://ghr.nlm.nih.gov/gene/KCNQ2#conditions.