A descriptive pilot study of mitochondrial mutations & clinical phenotype in fibromyalgia syndrome

Background & objectives: Fibromyalgia syndrome (FMS) is one of the most common chronic pain conditions of unknown aetiology. Mitochondrial dysfunction has been reported in FMS with some studies reporting the presence of mitochondrial mutation namely A3243G, which also causes mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes. This pilot study was conducted to assess this mutation and also detect large deletions in mitochondrial DNA (mtDNA) in patients with FMS. Methods: Thirty female patients with FMS participated and 30 matched controls were included. Genomic DNA was subjected to polymerase chain reaction (PCR) amplification using specific primers followed by restriction digestion with Apa I enzyme to detect the specific A3243G mtDNA mutation. Long-range PCR was done in two sets to detect the large deletions in the mtDNA. Biochemical parameters including thyroid-stimulating hormone and vitamin D levels were also looked at. Results: None of the patients were found to carry the common mutation or large deletions. Low vitamin D level was a common finding. Hypothyroidism was found in a few patients. Interpretation & conclusions: Although the common mutation or large mtDNA deletions were not detected in blood mtDNA in the FMS patients, mutations in the muscle and sequence variation in mtDNA remained a possibility. Future studies in both blood and muscle tissue including mtDNA sequencing are warranted in such patients to determine if a subset of FMS patients have mitochondrial myopathy