Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Dorsal Root Ganglia/Sympathetic Ganglia Sodium Channels Gene Polymorphisms in Fibromyalgia.

Vargas-Alarcon,  Gilberto, Alvarez-Leon,  Edith, Fragoso,  Jose-Manuel, Vargas,  Angelica, Martinez,  Aline, Vallejo,  Maite, Martinez-Lavin,  Manuel

Background:

A consistent line of investigation suggests that autonomic dysfunction may explain the multi-system features of fibromyalgia (FM), and that FM is a sympathetically maintained neuropathic pain syndrome. Dorsal root ganglia (DRG) are potential sympathetic-nociceptive short-circuit sites. Sodium channels located in DRG (particularly Nav1.7) act as molecular gatekeepers for pain detection. Nav1.7 is encoded in gene SCN9A of chromosome 2q24.3 and is predominantly expressed in the DRG pain-sensing neurons and sympathetic ganglia neurons. Several SCN9A sodium channelopathies have been recently recognized as the cause of rare painful-dysautonomic syndromes such as paroxysmal extreme pain disorder and primary erythermalgia (Ann N Y Acad Sci. 2010;1184:196, Med Hypotheses. 2009;72:64). SCN9A polymorphisms (particularly rs6746030) have been linked to altered pain perception (Proc Natl Acad Sci USA 2010;107:5148).

Objective:

To identify associations between fibromyalgia and several Nav1:7 polymorphisms encoded in gene SCN9A.

Methods:

We studied 73 Mexican women with FM according to the 1990 ACR criteria and 48 Mexican women who considered themselves healthy. All participants filled out the Fibromyalgia Impact Questionnaire (FIQ). Genomic DNA from whole blood containing EDTA was extracted by standard techniques. The following SCN9A single-nucleotide polymorphisms (SNPs) were studied: rs4371369, rs4387806, rs4453709, rs4597545, rs6746030, rs6754031, rs7607967, rs12620053, rs12994338, and rs13017637. SNPs were analyzed by 5-exonuclease TaqMan assays on a 7900HT fast real-time PCR system.

Results:

Are summarized in table 1. Rs6754031 nucleotide distribution was significantly different in both groups (p = 0.036) mostly due to an absence of GG genotype in controls. Interestingly, patients with this rs6754031 GG genotype had higher total FIQ scores, than patients with the other two rs6754031 genotypes (p = 0.039). Table 2.

Table 1. Nucleotide distribution.

Rs-6754031PatientsControlsP value
n7348 
Age (mean ± SD)44.7 ± 12.842.8 ± 12.3ns
Genotypen (%)n (%) 
GG8 (11)0 (0) 
GT24 (33)15 (31)0.036
TT41 (56)33 (69) 

Table 2. Total FIQ score in patients with Rs-6754031

Rs-6754031 GenotypePercentile 25FIQ scoreP value
  MedianPercentile 75 
GG69.7480.3888.740.039
GT58.5563.2977.53 
TT64.2371.2577 

Conclusions:

In this ethnic group, a disabling form of FM was associated to a particular SCN9A gene variant. These preliminary results raise the possibility that patients with severe FM may have a sodium channelopathy.

Financial support: American Fibromyalgia Syndrome Association.

To cite this abstract, please use the following information:
Vargas-Alarcon, Gilberto, Alvarez-Leon, Edith, Fragoso, Jose-Manuel, Vargas, Angelica, Martinez, Aline, Vallejo, Maite, et al; Dorsal Root Ganglia/Sympathetic Ganglia Sodium Channels Gene Polymorphisms in Fibromyalgia. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :96
DOI: 10.1002/art.27865

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