Abstract
BACKGROUND Potassium sodium-activated channel subfamily T member 1 (KCNT1)-related developmental and epileptic encephalopathy (DEE) is a rare and serious neurological condition attributed to damaging alterations in the KCNT1 gene, which encodes a sodium-activated potassium channel involved in neuronal excitability. It typically manifests in infancy with drug-resistant seizures, developmental delay, and hypotonia. Diagnosis is determined using whole-exome sequencing. Although KCNT1-related epilepsy is considered as a rare disorder, reporting such individual cases may help broaden the clinical and genetic spectrum of this condition. This report describes a Bahraini girl who first presented with symptoms at 2 weeks of age and at the time of this report was 4 years old, with developmental delay and epilepsy of infancy with migrating focal seizures (EIMFS), and early-onset DEE, associated with KCNT1 gene mutation. CASE REPORT A previously healthy term female baby presented at 2 weeks of age with focal seizures that progressed to intractable migrating focal epilepsy. At 4 months, she developed developmental regression, losing the ability to roll over, social-smile, and make eye contact. Neurological examination revealed central hypotonia with poor visual interaction. Electroencephalogram (EEG) showed multifocal epileptiform discharges with migrating seizure activity. Brain magnetic resonance imaging (MRI) and metabolic investigations were normal. Whole-exome sequencing identified a heterozygous KCNT1 variant, confirming developmental and epileptic encephalopathy type 14 (DEE14). CONCLUSIONS This case highlights the importance of timely genetic testing in infants showing severe epilepsy and developmental issues. To better understand the phenotypic variability and clinical course of KCNT1-related epileptic encephalopathy, more case reports are required. Identifying a KCNT1 mutation provides diagnostic clarity, supports precise prognosis and genetic counseling, and may help evaluate future targeted treatments.