Association of polymorphism of the enzyme catechol-o-methyltransferase with fibromialgic syndrome and its clinical repercussions

Abstract

Background: Fibromyalgia syndrome (FMS) is a clinical condition that mostly affects women of working age, with chronic diffuse pain, physical disability, mood swings, anxiety, fatigue and insomnia. Although its pathophysiology is not fully understood, it is believed that there are genetic contributions to its origin. There is evidence that some single nucleotide polymorphisms (SNPs) can change the function of proteins that participate in pain modulation, increasing the individual's susceptibility to pain processes. Catechol-O-methyltransferase (COMT) is an enzyme responsible for the inactivation of catecholamines in the central nervous system, participating in descending nociceptive inhibitory pathways. Polymorphisms in the gene encoding COMT can impair its formation and, consequently, its function, accentuating painful conditions in FMS patients. This study verified the association of SNPs rs4680, rs6269, rs4633 and rs4818 of the COMT gene with clinical aspects in patients with FMS undergoing treatment in public and private health services in Cuiabá, Mato Grosso Estate, Brazil. Methods: Forty-seven volunteers who underwent medical follow-up by FMS were selected, in which the Fibromyalgia Impact Questionnaire, the Beck’s Depression and Anxiety Inventories, the Insomnia Severity Index and the Mini-Mental State Examination were applied, in order to evaluate the clinical repercussions of the disease. Blood samples were collected for genetic evaluation. The DNA was extracted by salting out and the SPNs were evaluated by real time reverse transcription polymerase chain (RT-PCR). The association between clinic and SPNs was tested by the Fisher's exact test. A 95% CI and p value < 0.05 were adopted. Results: The results showed that there was no association between such SNPs and the participants' clinic regarding the tests used. Conclusions: This study showed that, although the disease has an important impact on patients' daily lives, increasing the chances of depression, anxiety, insomnia and cognitive losses, it is not associated with the SNPs researched. Further investigations, with larger samples, are needed to assess these and other associations between genetics factors and FMS.