No relevant excess prevalence of myotonic dystrophy type 2 in patients with suspected fibromyalgia syndrome

Between November 2011 and April 2014, 398 patients with suspected FMS who had been assessed by a rheumatologist participated in this cross-sectional study. 95% of the study population was female, with a mean age of 42 years. The final ICD-9 diagnoses were collected, in 96% the diagnosis was FMS. 92% met the 2010 American College of Rheumatology (ACR) diagnostic criteria for FMS. A questionnaire including neuromuscular symptoms was completed. Creatine kinase was determined, and genetic testing for DM2 was conducted in all patients. DM2 was established in only one patient (0.25%, 95% CI 0.04-1.4%), thus disapproving our hypothesis of a relevant prevalence of 2%. Our results suggest that patients with suspected FMS should not routinely be tested for DM2.