Screening for the presence of FMR1 premutation alleles in a Spanish population with fibromyalgia

Fragile X mental retardation 1 (FMR1) premutation carriers, who are at risk of having children with fragile X Syndrome, were initially considered as clinically unaffected. However, recent clinical and molecular studies have shifted this point of view. The incidence of premutation in the general population is substantial. Apart from the well-documented fragile X-associated tremor-ataxia and fragile X premature ovarian insufficiency, there is a broad constellation of symptoms including depression, anxiety, muscle pain, autoimmune and thyroid disease, chronic fatigue, and fibromyalgia that has been described, particularly in females with the premutation (55-200 repeats). Fibromyalgia (FM) is the most common cause of widespread pain and comprises a heterogeneous group of patients, affecting 2-3 % of the general population. We analyzed the FMR1 gene in a cohort of females diagnosed with fibromyalgia in order to assess the incidence of premutated alleles. CGG repeat size was determined in 353 females suffering from FM and results were compared with a control group. Four premutated carriers in the FM group were detected. The observed incidence is higher than that described for a normal female population (1/88 vs 1/250). The early detection of premutation carriers for the FMR1 gene among individuals diagnosed with fibromyalgia is important and would be helpful in correct genetic counseling of patients and their families, who may be at risk of having children with fragile X syndrome, the most common known cause of inherited intellectual disability and autism. Our data should be cautiously interpreted based on just this study; nevertheless, screening for the FMR1 gene in FM patients at least with presentations suggestive of FMR1 gene-related disease seems recommendable.