KCNQ2 gene
The KCNQ2 gene provides instructions for making potassium channels that regulate electrical signaling in the brain, and mutations in this gene are linked to various forms of epilepsy.
Normal Function
The KCNQ2 gene belongs to a family of genes that create potassium channels. These channels transport potassium ions into and out of cells, which is essential for generating and transmitting electrical signals. Channels containing the KCNQ2 protein are active in brain neurons, where they transmit a signal called the M-current. This current prevents neurons from becoming constantly active or over-excitable. These channels can function alone or by interacting with subunits from the KCNQ3 gene to produce a stronger M-current.
Health Conditions Related to Genetic Changes
Benign familial neonatal seizures
Benign familial neonatal seizures (BFNS) is a condition involving recurrent seizures in newborns. Mutations in the KCNQ2 gene lead to a reduction or alteration of the M-current, causing excessive neuronal excitability. Researchers suggest that a 25 percent reduction in the M-current is sufficient to cause these seizures, which typically resolve within a few months.
Early-onset epileptic encephalopathy
More severe mutations in the KCNQ2 gene can lead to early-onset epileptic encephalopathy, characterized by:
- Epilepsy that begins in the first weeks of life.
- Profound intellectual disability.
- Low muscle tone (hypotonia) or stiff muscles.
- Limited response to treatment.
In these cases, the abnormal KCNQ2 protein may bind to normal subunits but prevent the channel from functioning, leading to a severe reduction of the M-current and subsequent brain dysfunction.