Contiguous deletion of KCNQ2 and CHRNA4 may cause a different disorder from benign familial neonatal seizures

Benign familial neonatal seizures (BFNS) is an autosomal dominant disorder associated with heterozygous mutations of either the KCNQ2 or KCNQ3 gene. Most cases have mutations of the KCNQ2 gene. A handful of cases with KCNQ2 and CHRNA4 deletions have been identified with different phenotypic presentations. Only two cases presented with typical BFNS features. Benign familial neonatal seizures is associated with normal exam and work-up, and seizure remission is seen in the first month of life. We report three unrelated individuals with KCNQ2 and CHRNA4 deletions, presenting with neonatal seizures and developmental delay. Their seizures started within one week after birth; all required antiepileptic drugs. Each had normal brain magnetic resonance imaging and at least two electroencephalograms with either normal or abnormal findings. All were developmentally delayed. None presented with autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) phenotype associated with CHRNA4 mutation. This study supports reports of KCNQ2 and CHRNA4 deletions associated with phenotypes different from typical BFNS.