ANÁLISE DO POLIMORFISMO A118G DO GENE OPRM1 EM PACIENTES COM FIBROMIALGIA E CONTROLES.

Abstract

Fibromyalgia can be defined as a syndrome of chronic and diffuse musculoskeletal pain, with non-inflammatory characteristics. With the etiological processes still unclear, this disease has assumed an increasingly important role worldwide, with a prevalence of 2% estimated in the world population. Currently, the most discussed pathological mechanism for the disease is a change in pain perception mediated by excitatory and inhibitory neurotransmitters in the central nervous system. In this context are very relevant targets the endogenous opioids and their correlated receptors. The OPRM1 gene encoding the major opioid receptor called mu-opioid receptor, presents a single nucleotide polymorphism (SNP) at position 118 (A118G) that significantly affects the response to endogenous and synthetic opioids. Objectives: The objectives of this study were to compare the frequency of A118G polymorphism in the OPRM1 gene in two groups of women, including 50 women affected by fibromyalgia and 50 unaffected, as well as to investigate the possible associations between the A118G polymorphism with clinical and functional symptoms of the disease. Methodology: Patient´s clinical and functional pain symptoms were assessed by using the Fibromyalgia Impact Questionnaire (FIQ). The A118G polymorphism of the OPRM1 gene was analyzed by polymerase chain reaction followed by analysis of restriction fragment length polymorphism DNA was extracted from peripheral blood samples obtained from the two groups of women. Descriptive and comparative statistical analysis were performed and the results obtained. Results: The results of clinical and functional pain symptoms from fibromyalgia patients, obtained by the FIQ, confirmed the clinical severity of the patients selected in this study. The allele frequencies obtained for the two groups were: A (86,0%) and G (14,0%) for patients with fibromyalgia and A (87,8%) and G (12,2%) for controls. The AA genotype frequencies were found (74,0%) and AG (24,0%) and GG (2,0%) for patients with fibromyalgia and AA (77.6%) and AG (20.4%) and GG (2,0%) for the controls. Conclusions: No statistically significant difference was detected between the group of patients with fibromyalgia and control patients. The A118G polymorphism of the OPRM1 gene was not associated with clinical and functional pain symptoms of the patients analyzed in this study.