SCN5A and channelopathy: SCN1B-linked channelopathy variants have shown abnormalities in modulation of INa density and voltage-dependent properties when expressed in heterologous cells.7,45-49 Here, we assessed the effects of β1-p.R89C co-expression on INa density expressed by the tetrodotoxin-sensitive channels, Nav1.1 or Nav1.6, or the tetrodotoxin-resistant channel, Nav1.5.