KCNQ2 variants in neonatal onset of self-limiting epilepsy.

Objectives: To describe the clinical presentation and response to medication in two cases of self-limiting KCNQ2-related epilepsy.

Case presentation: Both infants were born at term and had tonic seizures during the first two weeks after birth. The first infant had frequent seizures at presentation requiring two weeks of hospital stay. The second infant was born three months later and was only briefly admitted to hospital. The first infant was conceived by sperm for in vitro fertilization donated by the second case's father. Trio genome sequencing in case one successfully identified a pathogenic KCNQ2 variant in the proband, which was also confirmed in the proband for case 2 by targeted Sanger sequencing. The second case's father was an asymptomatic carrier of the pathogenic variant. Both infants responded to Carbamazepine. At more than six months of age, they are currently seizure free and developmentally normal.

Conclusions: Self-limited epilepsies with onset in neonates (SeLNE) are usually autosomal dominant disorders characterized by the neonatal onset of focal motor seizures and the absence of neurodevelopmental complications. KCNQ2, encoding a voltage-gated potassium channel subunit, K_V7.2, is the most common gene associated with SeLNE. Careful history taking and a genetic diagnosis can help to make the correct therapeutic choices.