Objectives: This study aimed to investigate the genetic infl uence of the T102C polymorphism of the 2A serotonin receptor gene (HTR2A) and its interaction with environmental aspects, such as exposure to noise, traffi c, climate, and opportunities to acquire new information, physical protection, and security, among others, as possible risk factors for developing fi bromyalgia syndrome (FMS). Methods: Forty-one FMS patients and 49 controls were evaluated. Environmental factors were evaluated by application of the V domain of the WHOQOL-100 questionnaire. Patients were asked that their answers represented only the periods preceding the onset of symptoms. The T102C variant of the HTR2A gene was determined through PCR/RFLP. Results: Among patients, the frequency of carriers of the 102C allele was higher than in controls (76.5% vs. 50%; P = 0.028). The scores of the V domain were lower in patients than in controls, indicating a worst perception of the environmental quality by patients (P < 0.001). The factor "lack of opportunities for acquiring new information and skills" increased the chance of developing FMS by almost 14-fold (P = 0.009). The factor "low quality of social care and health" together with the presence of the 102C allele also increased this chance by more than 90-fold (P = 0.005). However, carriers of the same allele who have high quality social care and health are not at a higher risk to develop FMS. Conclusion: These data suggest that these factors may predispose to FMS, especially in carriers of the 102C allele. However, studies with larger samples are required to confi rm this hypothesis.

Introduction: Fibromyalgia is a multifactorial disease, of which etiology is based on interaction between genetic susceptibility and environment. However, few studies attempted to identify the risk factors. Objective: To investigate the genetic influence and its interaction with environmental quality and stress, as possible risk factors for fibromyalgia development. Patients and Methods: This cross-sectional study investigated two groups of women, of which 47 had a clinical diagnosis of fibromyalgia, and 41 women comprising thre control group, all from the town of Novo Hamburgo, RS. The apolipoprotein E (APOE) gene polymorphism was analyzed in DNA extracted from total blood, in both samples. Environmental factors were studied through Lipp's Inventory of Stress Symptoms for Adults and by applying the WHOQOL-100 domain V. Results: Among the patients, more women had high stress levels when compared to the control sample (P < 0.001); moreover, the average scores of the WHOQOL-100 domain V, which analyze environment quality, were lower in this group (P < 0.001). APOE genotypic and allelic frequencies were similar between the two groups. Multivariate analysis showed that low WHOQOL-100 scores increase the chance of disease development by 57.7 times (P < 0.001), and that high stress levels were related with the disease (OR = 197.2; P < 0.001). This approach pointed out an interaction between stress and presence of E*2 allele (P = 0.028). Fibromyalgia was much more frequent in patients with high stress levels that were E*2 non-carriers (estimated OR = 265.1), when compared to patients with the same stress level, but E*2 carriers (estimated OR = 1.06). Conclusion: E*2 allele presence could have a protective action regarding the association between fibromyalgia and stress.