SCN4A and amyotrophic lateral sclerosis: Antiarrhythmic medicines such as mexiletine, which inhibit inward Na current, are effective for treating patients with the Nav1.4 gene mutation and ALS patients to prevent skeletal muscle stiffness and cramps.3,4 However, antiarrhythmic medicines often show adverse effects and insufficient efficacy.24 Therefore, we suggest that GJG may be useful as a complementary medicine for muscle stiffness and cramps caused by Nav1.4 dysfunction.