National Organization for Rare Disorders, Inc.
It is possible that the main title of the report KCNQ2 Encephalopathy is not the name you expected.
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.
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- Website: http://www.epilepsyfoundation.org
Intractable Childhood Epilepsy Alliance (ICE)
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- 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
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- 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".
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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
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