SCN9A gene mutations are found in erythromelalgia, characterized by severe burning pain and superficial reddening of the skin (erythema); small fiber neuropathy, characterized by servere autonomic dysfunction and neuropathic pain; and, paroxysmal extreme pain disorder, characterized by episodic erythema and painful burning sensations from the lower extremities (waist downward) (Dib-Hajj et al., 2008; Han et al., 2012; Wu et al., 2013; Hoffmann et al., 2018; Hameed, 2019). This evidence concerns the gene SCN9A and Erythema.