Authors :
Presenting Author: Mark LaCoursiere, MS – Boston Children's Hospital
Zachary Stayn, BS – Harvard University
Annapurna Poduri, MD, MPH – Boston Children's Hospital
Rationale:
An estimated 50-70% of pediatric-onset epilepsy with presumed genetic causes have no genetic diagnosis. Often, genome-wide association studies and cohort sequencing studies implicate plausibly explanatory genes, but additional evidence is needed before any gene can be considered causative. One such recently implicated gene, identified with variants in two patients with genetic generalized epilepsy with absence seizures, is CAMSAP3. CAMSAP3 is responsible for regulating non-centrosomal microtubule acetylation, which is required for normal axon development. However, there is no in vivo evidence for CAMSAP3’s role in human epilepsy.
Methods:
Here we characterized seizure activity and hyperexcitability in a CRISPR/Cas9-generated loss of function (LOF) zebrafish camsap3 model. Characterization included detection of seizure-like swimming behavior with motion tracking software as well as single electrode local field potential (LFP) recordings in larval tectum. Developmental abnormalities of larval tectum were assayed via GABAergic interneuron quantification and acetylated alpha-tubulin immunohistochemistry.
Results:
We observed an increase in abnormal seizure-like swimming behavior in response to proconvulsant in larval zebrafish as compared to control. We also observed an increase in spontaneous spike and burst electrical activity via LFP among camsap3 mutants. Additionally, microscopy of larval tectum revealed a significant reduction in mutant GABAergic interneurons as well as an increase and disorganization of acetylated alpha-tubulin.
Conclusions:
Zebrafish camsap3 LOF results in abnormal CNS development, leading to network disinhibition and a seizure-like phenotype. Together this data provides further evidence for CAMSAP3’s causative role in human epilepsy.
Funding: BCH Translational Research Program