KCNQ2 Encephalopathy

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It is possible that the main title of the report KCNQ2 Encephalopathy is not the name you expected.

Disorder Subdivisions

  • None

General Discussion


KCNQ2E typically presents with seizures in the first week of life. Seizures appear as stiffening of the body (tonic) often associated with jerking and changes in breathing or heart rate. The seizures are usually quite frequent (many per day) and often difficult to treat. Typically, the seizures are associated with abnormal brain wave patterns on EEG during this time. The seizures in KCNQ2E often resolve within months to years but children have some degree of developmental impairment involving one or more domains (motor, social, language, cognition). This can range from mild to severe depending on a number of different factors. Some children may also have autistic features.


The story of KCNQ2E begins with the identification and characterization of another related disorder, benign familial neonatal seizures (BFNS). This condition was initially described as a syndrome in 1964 by Rett and Teubel. They reported a family with eight affected individuals over 3 generations. The youngest infant had the onset of seizures at three days of age described as tonic-clonic events occurring multiple times per day. The EEG was normal in between seizures and children developed appropriately after the seizures stopped. This typically happened later in infancy. Over the next twenty years, additional families with similar stories were described. In a few instances, seizures persisted into later life but outcomes were otherwise favorable. The pattern of inheritance was determined to be autosomal dominant (see the Affected Populations section for further explanation) and genetic testing linked the disorder to the long arm of chromosome 20 (see the Causes section for further definition). In 1998, researchers identified a gene in the region that appeared similar in structure to a potassium channel within the heart. This new gene was named, according to convention, KCNQ2. Subsequently, several families were identified in which the outcome was not benign having either persistent seizures that did not respond to medication, developmental impairment, or both. This prompted a group of researchers to screen patients with severe neonatal epilepsy syndromes for mutations in KCNQ2. Eight children were identified from the group of 80 patients and the children shared many characteristics. Since that initial paper in 2011, many more individuals have been diagnosed and the syndrome has been defined further.

Supporting Organizations

Epilepsy Foundation

8301 Professional Place
Landover, MD 20785-7223
Tel: (866)330-2718
Fax: (877)687-4878
Tel: (800)332-1000
Email: ContactUs@efa.org
Website: http://www.epilepsyfoundation.org

Intractable Childhood Epilepsy Alliance (ICE)

PO Box 365
250 Lewisville-Vienna Road
Lewisville, NC 27023
Tel: (336)918-9440
Fax: (336)946-1197
Website: http://www.icepilepsy.org

KCNQ2 CURE Alliance

3700 Quebec Street, Unit 100-118
Denver, CO 80202
Tel: 303-887-9532
Email: info@kcnq2cure.org
Website: http://www.kcnq2cure.org/

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders (NORD). For a full-text version of this report, go to www.rarediseases.org and click on Rare Disease Database under "Rare Disease Information".

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only.

It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report.

This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.

Last Updated:  3/8/2016
Copyright  2016 National Organization for Rare Disorders, Inc.