Larger studies are required to examine this association however it raises interest in genetic candidates associated with pain conditions with prominent dysautonomia such as SCN9A [OMIM: 603415] in paroxysmal extreme pain disorder (PEPD) and SCN11A [OMIM: 604385] in familial episodic pain syndrome (FEPS3) (34,35). This evidence concerns the gene SCN11A and familial episodic pain syndrome with predominantly lower limb involvement.