The spectrum of KCNQ2-related disorders – three case reports

Introduction: KCNQ2-related disorders are channelopathies characterized by neonatal-onset seizures, with a clinical spectrum ranging from self-limited neonatal epilepsy to neonatal epileptic encephalopathy. We report three cases that illustrate this phenotypic variability. Case reports: A 30-month-old male with an uneventful pregnancy and delivery developed seizures on day three of life. An EEG showed bilateral epileptiform activity. The seizures resolved after treatment with phenobarbital until four months of age. The patient presented normal neurodevelopment and unremarkable MRI, metabolic studies, and follow-up EEGs. Genetic testing revealed a KCNQ2 exon 15 deletion. Two 25-month-old female twins, born late preterm, developed seizures on day two of life with multifocal epileptiform activity. Their status epilepticus was unresponsive to levetiracetam but responded to phenytoin, with subsequent seizure control with carbamazepine. One twin has mild developmental delay, while the other has normal development. A KCNQ2 missense variant was identified. Discussion: These cases underscore the genotype-phenotype variability and the central role of genetic testing in evaluating and managing neonatal seizures.