Fibromyalgia (FM) is a chronic pain syndrome characterized by generalized skeletal muscle chronic pain. Its etiology is not well defined, because there are several factors that may trigger it such as physical and/or emotional stresses, or a genetic susceptibility, involving serotonergic, dopaminergic and catecholaminergic paths. The objective of this study was to investigate the association between the strength of the lower limb, genetic polymorphism of the serotonin receptor gene HTR
In this observational study of case-control type 48 women were evaluated who belonged to the group with FM (52 ± 12 years) and 100 women in the control group (58 ± 11 years). Socio demographic and anthropometric data were collected and peripheral blood samples for DNA extraction; genotypic analyzes were performed by means of PCR in real time by TaqMan® system. The lower limb muscle strength was assessed through the test of sitting down and standing up for 30 s. The chi-square test or Fischer Exact was used for possible associations among the variables; the t-test for independent samples was used to compare the averages among the groups; the value of significance adopted was 5%.
There was an association between the polymorphism of the HTR2A gene with FM, demonstrating that carriers of the genotype GG have 24.39 times more likely to develop the syndrome (IC95% 5.15-115.47; p = 0.01). It was observed an association between FM and the test to sit and stand up demonstrating that women with fibromyalgia have lower limb muscle strength (p = 0.01). The study showed that the white race has 3.84 times more likely to develop FM (p = 0.01).
The results of this study suggest that women of Caucasian ethnicity with GG genotype or G allele presented greater risk of developing fibromyalgia and that these patients have lower limb muscle strength compared to the control group.