Mouse models of Slc35a2 brain mosaicism reveal mechanisms of mild malformations of cortical development with oligodendroglial hyperplasia in epilepsy.

Objective: Brain somatic variants in SLC35A2 were recently identified as a genetic marker for mild malformations of cortical development with oligodendroglial hyperplasia in epilepsy (MOGHE). The role of SLC35A2 in cortical development and the contributions of abnormal neurons and oligodendrocytes to seizure activity in MOGHE remain largely unexplored.

Methods: Here, we generated a novel Slc35a2 floxed allele, which we used to develop two Slc35a2 conditional knockout mouse lines targeting (1) the Emx1 dorsal telencephalic lineage (excitatory neurons and glia) and (2) the Olig2 lineage (oligodendrocytes).

Loss of Slc35a2 alters development of the mouse cerebral cortex.

Brain somatic variants in SLC35A2, an intracellular UDP-galactose transporter, are commonly identified mutations associated with drug-resistant neocortical epilepsy and developmental brain malformations, including focal cortical dysplasia type I and mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy (MOGHE). However, the causal effects of altered SLC35A2 function on cortical development remain untested. We hypothesized that focal Slc35a2 knockout (KO) or knockdown (KD) in the developing mouse cortex would disrupt cortical development and change network excitability.

Rapid modeling of an ultra-rare epilepsy variant in wild-type mice by in utero prime editing.

Generating animal models for individual patients within clinically-useful timeframes holds great potential toward enabling personalized medicine approaches for genetic epilepsies. The ability to rapidly incorporate patient-specific genomic variants into model animals recapitulating elements of the patient's clinical manifestations would enable applications ranging from validation and characterization of pathogenic variants to personalized models for tailoring pharmacotherapy to individual patients. Here, we demonstrate generation of an animal model of an individual epilepsy patient with an ultra-rare variant of the NMDA receptor subunit GRIN2A, without the need for germline transmission and breeding.

Loss of alters development of the mouse cerebral cortex.

Brain somatic variants in are associated with clinically drug-resistant epilepsy and developmental brain malformations, including mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy (MOGHE). encodes a uridine diphosphate galactose translocator that is essential for protein glycosylation; however, the neurodevelopmental mechanisms by which disruption leads to clinical and histopathological features remain unspecified. We hypothesized that focal knockout (KO) or knockdown (KD) of in the developing mouse cortex would disrupt cerebral cortical development through altered neuronal migration and cause changes in network excitability.