A 4-Year-Old Bahraini Girl With Developmental Delay and Epilepsy of Infancy With Migrating Focal Seizures Associated With KCNT1 Gene Mutation

Rare disease 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.