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References OMIM Gene GeneReviews HGMD HGNC
last update : 19-12-2009
Symbol ETHA
Location 2q24.3
Name erythermalgia, primary
Other name(s)
  • erythermalgia, familial
  • inherited erythromelalgia/erythermalgia
  • Corresponding gene SCN9A
    Other symbol(s) IEM
    Main clinical features
  • neuropathy characterized by pain and redness of the extremities that is triggered by warmth
  • childhood onset of episodic symmetrical red congestion, vasodilatation, and burning pain of the feet and lower legs provoked by exercise, long standing, and exposure to warmth
  • characterized by attacks of intense burning pain in the extremities local red-purple discoloration with minor congestion and increased temperature, slowly progressive
  • Genetic determination autosomal dominant
    Function/system disorder dermatology
    Type disease
    Gene product
    Name sodium channel, voltage-gated, type IX, alpha
    Gene mutationChromosome rearrangementEffectComments
    unknown   abnormal protein/gain of function produces threshold currents and is selectively expressed within sensory neurons including nociceptors
  • may be a neuropathic disorder of the small peripheral sensory and sympathetic neurons, and may be caused by hyperexcitability of SCN9A
  • A863P mutant channels produce hyperexcitability in dorsal root ganglion neurons, which contributes to the pathophysiology of ETHA
  • selective effect of Carbamazepine on the mutant SCN9A appears to explain the ameliorative response to treatment in any cases (Fischer 2009)
  • activating mutations cause severe episodic pain in paroxysmal extreme pain disorder and primary erythermalgia (Reimann 2010)