KCNQ2 encodes the Kv7.2 subunit of a voltage-gated potassium channel in neurons. This channel generates the “M-current” — a stabilizing electrical brake that keeps neurons from firing too rapidly. When KCNQ2 is mutated, that brake can fail, and seizures can begin in the first days of life.
Most KCNQ2 developmental and epileptic encephalopathy cases arise from de novo mutations — spontaneous changes that are not inherited. Understanding the specific variant a child carries is the first step toward a targeted therapy.