Hemorrhagic shock and encephalopathy syndrome in a patient with a de novo heterozygous variant in KIF1A

Identification of Genetic Variants in Status Epilepticus Associated With Fever

PURPOSE

Status epilepticus associated with fever (SEF) is often encountered in pediatric emergency departments, and some patients develop neurological emergencies, such as acute encephalopathy (AE). Although numerous genetic variants of developmental and epileptic encephalopathy (DEE) have been reported, the frequency of these disease-associated variants of SEF is unknown. The first aim of this study was to investigate the associated genetic variants of SEF. The second aim was to compare the variations in genes between SEF and DEE.

METHOD

This retrospective, clinical observational study included patients with SEF or DEE who visited Kobe University Hospital or Kobe University affiliated hospitals and provided consent for a genetic diagnosis of SEF or DEE between January 1, 2021, and December 31, 2022.

FINDING

Fifteen patients with SEF and 27 patients with DEE consented to a genetic diagnosis and were included in the study. The detection rate of genetic variants was lower in patients with SEF (26.7%) than in those with DEE (63.0%), although there is no statistically significant difference (p = 0.05, Fisher's exact test). Analysis of patients with DEE revealed a wide variety of causative genes for DEE (16 different genes), whereas in SEF cases, only SCN1A variants were detected.

CONCLUSION

Our study is the first to clarify the detection rates of different genetic variants in SEF. Patients with SEF may have less genetic involvement in the onset of epileptic seizures, compared to those with DEE.

Presynaptic perspective: Axonal transport defects in neurodevelopmental disorders

Disruption of synapse assembly and maturation leads to a broad spectrum of neurodevelopmental disorders. Presynaptic proteins are largely synthesized in the soma, where they are packaged into precursor vesicles and transported into distal axons to ensure precise assembly and maintenance of presynapses. Due to their morphological features, neurons face challenges in the delivery of presynaptic cargos to nascent boutons. Thus, targeted axonal transport is vital to build functional synapses. A growing number of mutations in genes encoding the transport machinery have been linked to neurodevelopmental disorders. Emerging lines of evidence have started to uncover presynaptic mechanisms underlying axonal transport defects, thus broadening the view of neurodevelopmental disorders beyond postsynaptic mechanisms. In this review, we discuss presynaptic perspectives of neurodevelopmental disorders by focusing on impaired axonal transport and disturbed assembly and maintenance of presynapses. We also discuss potential strategies for restoring axonal transport as an early therapeutic intervention.

Dravet syndrome and hemorrhagic shock and encephalopathy syndrome associated with an intronic deletion of SCN1A

OBJECTIVE

Hemorrhagic shock and encephalopathy syndrome (HSES) is a serious condition that requires intensive care and is associated with a high mortality rate. However, its pathogenesis remains unclear. In the present study, a genetic analysis was performed to determine the genetic background of patients with clinically suspected Dravet syndrome (DS) who developed HSES.

METHODS

Whole exome sequencing was performed, followed by minigene analysis of the intron variant detected by whole exome sequencing to confirm its effect on splicing.

RESULTS

Whole exome sequencing revealed a novel 21-bp deletion in intron 3 of SCN1A NM_001165963.4 (NC_000002.11:g.166073675_166073695del). This deletion was not found in the patient's parents and was proven to be de novo. Minigene analysis revealed an aberrant mRNA lacking 40 and 106 bp from the 5' end of exon 4 of SCN1A. Therefore, we diagnosed this case as DS due to the deletion in intron 3 of SCN1A.

CONCLUSIONS

We report a case of DS with HSES caused by a 21-bp deletion in the intron of SCN1A that was confirmed by minigene analysis. The present case met Levin's criteria for HSES and the splicing analysis of SCN1A is an important finding. This study has important implications for understanding HSES pathogenesis.