About KCNQ2 › KCNQ2-related disorders
Understanding KCNQ2
What are KCNQ2-related disorders?
KCNQ2-related disorders are a group of rare genetic conditions caused by variants (or changes) in the KCNQ2 gene. Here is what the gene does, how symptoms can differ, and what to expect from diagnosis.
At a glance
1 in 17,000
newborns is estimated to be diagnosed with a KCNQ2-related disorder
Week 1
when seizures, the most common first sign, usually begin
2 forms
at opposite ends of a spectrum, with many people in between
Top cause
KCNQ2 variants are one of the most common causes of genetic neonatal epilepsies
What is KCNQ2?
KCNQ2 is a gene. Its name describes what it builds, and it works as a chain of three parts, each one leading to the next.
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1 · The gene
An instruction manual
KCNQ2 tells your body how to build a specific protein called Kv7.2.
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2 · The protein
Kv7.2
Kv7.2 is an important piece of a potassium channel found in the brain.
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3 · The channel
A tiny gate
On nerve cells in the brain, it opens and closes to regulate potassium levels and help balance brain activity.
What are KCNQ2-related disorders?
KCNQ2-related disorders are a group of rare genetic conditions caused by variants (or changes) in the KCNQ2 gene. These variants can affect Kv7.2 abundance or function, which can make the brain prone to seizures.
It is estimated that 1 in 17,000 newborns is diagnosed with a KCNQ2-related disorder, making KCNQ2 variants one of the most common causes of genetic neonatal epilepsies.
Beyond seizures, KCNQ2-related disorders can include:
- Developmental delays
- Movement problems
- Behavioral changes
- Other non-seizure symptoms
Two ends of a spectrum
What are the symptoms?
For most individuals with a KCNQ2-related disorder, the first sign is seizures that begin within the first week of life. Other symptoms vary widely. Choose a topic below to compare the two forms.
Age of diagnosis
Milder end
Self-limited Neonatal Epilepsy (SeLNE)
Formerly BFNE
Often first week of life
Severe end
Developmental and Epileptic Encephalopathy (DEE)
KCNQ2-DEE
Often first week of life, but can appear later in early childhood
These two forms represent opposing ends of the symptomatic spectrum. Many individuals fall somewhere between these two presentations, and the factors contributing to symptom severity are not fully understood.
Read the KCNQ2 GeneReviews for more detailed clinical characterizations and descriptions of phenotypes associated with KCNQ2. · See life with KCNQ2-DEE
How are KCNQ2-related disorders diagnosed?
Most children with KCNQ2-related disorders are diagnosed within the first few weeks of life. The diagnostic process moves fairly quickly, but the emotional journey can feel overwhelming. Here’s what typically happens at each step:
- 1
Seizure recognition
Within the first few days of life, your baby shows unusual, repetitive movements: stiffening, rhythmic jerking, eye deviation, lip smacking, bicycling movements, or pauses in breathing.
- 2
EEG (electroencephalogram)
Your doctor orders an EEG, a test that measures the brain’s electrical activity using sensors placed on the scalp. In babies with KCNQ2-related disorders, EEGs can show a pattern called “burst suppression,” in which the brain’s activity alternates between bursts and flat, quiet periods.
- 3
Brain MRI
Your doctor may also order an MRI to get a detailed picture of the brain. In some cases, KCNQ2 variants can cause brain abnormalities that may be revealed by this scan.
- 4
Genetic testing
If a genetic epilepsy is suspected, a blood (or saliva) sample will be sent to a lab for testing. This step is required to confirm the diagnosis of a KCNQ2-related disorder. Results come back classified as:
Reading your genetic report →Pathogenic / Likely Pathogenic
Clear evidence that your child has a KCNQ2-related disorder
Variant of uncertain significance (VUS)
A KCNQ2 variant was found, but it’s unclear if it causes disease, meaning more research needs to be done
Benign / Likely Benign
The KCNQ2 variant is unlikely to cause symptoms
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