Genetic neonatal seizures in the neonatal intensive care unit: Diagnostic and prognostic implications for three families.

Objective: We investigated neonatal seizures in three probands admitted to the neonatal intensive care units and their affected family members.

Methods: Whole exome sequencing (WES) was performed along with confirmation by Sanger sequencing and segregation analysis. Copy number variant (CNV) analysis was also conducted. Neuroimaging, electroencephalography, and metabolic analysis revealed clinical phenotypes.

Results: Bi-allelic variants c.1025T>C and c.1150G>A in MOCS1 were found in twin girls with molybdenum cofactor deficiency. The c.1025T>C variant was novel. A c.877C>T variant in KCNQ2 co-segregated with seizures in a family. A de novo 6.25 Mb duplication on 2q24.3 encompassing SCN1A, SCN2A, and SCN3A was identified in a proband who demonstrated normal development without seizures on follow-up.

Significance: WES facilitated the molecular diagnosis of neonatal seizures in the study participants. Variants in the KCNQ2 and MOCS1 genes were classified as likely pathogenic based on our findings. The individual with a duplication of the sodium channel gene cluster on 2q24.3 exhibited additional phenotypes. Our investigation expanded the genotype-phenotype spectrum.