Interestingly, the null mouse model of Cntn1, encoding the IgSF-CAM contactin, which is a functional binding partner of VGSC β1 subunits (65, 66), has a similar phenotype to Scn1b null mice, including death by P18, severe ataxia, and cerebellar micro-organization defects with aberrant CGN axon guidance (67). Here, SCN1B is linked to cerebellar ataxia.