The failure of sodium channel blockers such as lidocaine and mexiletine to suppress arrhythmia in ERS is consistent with the reports of loss-of-function SCN5A mutations underlying ERS and animal studies demonstrating that INa blockade with pilsicainide increases susceptibility to VF (Watanabe et al., 2011; Koncz et al., 2014). Here, SCN5A is linked to amelogenesis imperfecta type 1G.