Among the described Nav1.7 gain of function mutations that are associated with inherited erythromelalgia (Dib-Hajj et al., 2007; Cheng et al., 2008, 2011; Cregg et al., 2013; Estacion et al., 2013; Vasylyev et al., 2014), the isoleucine to valine substitution (as that described for the cardiac and muscular disorders) was found in a Taiwanese family with the characteristic features of erythromelalgia. This evidence concerns the gene SCN9A and erythromelalgia.