The sodium channel protein type 8 subunit alpha (Na+ CP type VIIIalpha ) is a multi-pass, transmembrane protein that mediates the sodium ion permeability of excitable membranes. The three glycoproteins that comprise the voltage-gated sodium channel proteins include a pore-forming alpha subunit, a noncovalently associated beta1 subunit and a disulfide-linked beta2 subunit. The two beta subunits regulate the level of channel expression, modulate gating and function as cell adhesion molecules for cellular aggregation and cytoskeleton interaction. The alpha subunits of sodium channels type I and III are predominantly expressed in neuronal cell bodies and proximal processes, while type IIalpha subunits are more abundant along axons. Sodium channels are important for rapid signal transduction but also play a significant role in neuronal development. Defects of the SCN8A gene have exhibited detrimental effects on the growth of secondary motoneurons. Loss of SCN8A expression will result in progressive paralysis and early death.