We have recently shown that a gain-of-function variant in Kv7.2 voltage-gated potassium channel contributes to amelioration of pain in a mother carrying the Nav1.7-S241T mutation which causes inherited erythromelalgia, compared to her son with the same Nav1.7 mutation but wild-type Kv7.2 (Mis et al., 2019). This evidence concerns the gene SCN9A and erythromelalgia.