Nav2 hypomorphic mutant mice are ataxic and exhibit abnormalities in cerebellar development

► Nav2 is required for normal cerebellar development. ► Nav2/unc-53H2 homozygous mutants (Nav2−/−) are ataxic. ► The size of the cerebellum is reduced and foliation is disrupted in Nav2−/− mutants. ► Disappearance of the EGL in homozygous Nav2−/− mutants is delayed. ► Axon extension and migration of granule cells is defective in Nav2−/− mutants.