Connexion

GENATLAS PHENOTYPE

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

Mechanism(s)

Gene mutation	Chromosome rearrangement	Effect	Comments

unknown		abnormal protein/gain of function	produces threshold currents and is selectively expressed within sensory neurons including nociceptors

Remark(s)

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)