–      Background/Purpose: More than 20% of the general population suffer from functional syndromes. It has been reported that the mitochondrial polymorphism at position 16519 is associated with functional syndromes, such as migraine, cycling vomiting syndrome, irritable bowel syndrome, non-specific abdominal pain, chronic fatigue syndrome and complex regional pain syndrome. The aim of this study was to evaluate the association of polymorphism 16519 in patients with fibromyalgia (FM).

–      Methods: Patients with fibromyalgia according to the 1990 or 2010 ACR criteria and be able to provide informed consent and healthy controls were recruited for this study. Inclusion criteria were: age ≥ 18 years old, diagnosis of FM, and as exclusion criteria: patients with another rheumatic comorbidity. The protocol was approved by the Ethics Committee of the Hospital Central Dr. Ignacio Morones Prieto, San Luis Potosí, México. Statistical analysis was performed with X² test.

–      Results:  We included 40 FM patients and 36 controls, all patients were women. Mean age were 49.1years (SD 11years) in the group of FM and 43.2 years (SD 11.9 years) in the control group. The demographic characteristics of both groups are in table 1. In the FM group the average number of positive tender points was 10 (SD 5), with average Widespread Pain Index (WPI) of 10 (SD 5), average symptom Severity Score 7 (SD 2.7) and the Fibromyalgia Impact Questionnaire (FIQ) 52.8 (SD 19.3). The presence of the polymorphism 16519 in the group of FM was observed in 21/40 (53%) vs 29/36 (80.6%) of control group, with a p value of 0.010, OR 0.27 (IC 95% 0.080 – 0.82). We did not find association between the polymorphism and the severity score.

–      Conclusion: The polymorphism at position 16519 has been reported previously as a genetic factor predisposing individuals to develop functional syndrome; our results showed a negative association between this polymorphism and patients with fibromyalgia.