Ring chromosome 20: a pediatric potassium channelopathy responsive to treatment with ezogabine.

BACKGROUND: Ring chromosome 20 is a genetic disorder characterized by intractable epilepsy, behavioral problems, and cognitive deficit. The potassium channel-coding gene KCNQ2 is localized at the locus q13.3 on the chromosome 20, the most common site where the ring occurs. Ezogabine is the first potassium channel opener marketed in the United States.

PATIENTS: We describe an 8-year-old girl with mosaic ring chromosome 20 and refractory epilepsy who had a remarkable improvement in seizure control with ezogabine.

CONCLUSIONS: This is the first report using the new antiepileptic drug ezogabine to treat pediatric epilepsy. We hypothesize that ring chromosome 20 patients have epilepsy related to abnormalities in the potassium channels, making it susceptible for treatment with potassium channel openers.