Fibromyalgia in fragile X mental retardation 1 gene premutation carriers.

OBJECTIVE: FM is a disorder of altered pain regulation and is characterized by pain, fatigue, poor sleep and psychological impairments; thus, it is classified as a central sensitivity syndrome. Female carriers of a premutation in the fragile X mental retardation 1 (FMR1) gene frequently have widespread musculoskeletal pain and sometimes have been diagnosed with FM, especially if they have the motor signs of fragile X-associated tremor ataxia syndrome (FXTAS). Studies suggest that FM occurs in persons with a genetic predisposition. We describe the clinical features of female FMR1 premutation carriers with symptoms of FM. METHODS: A sample of patients was selected that participated in studies at two tertiary referral academic centres on the phenotype and therapy of FXTAS. RESULTS: This selected sample of patients, five female premutation carriers, has FM symptoms or diagnoses and other central sensitivity syndromes. CONCLUSION: Since FM affects 2-4% of the world's population and about 1 in 250 females are FMR1 carriers, a study screening females with FM for the presence of the FMR1 premutation is worthwhile. A finding of increased prevalence of FMR1 carriers among females with FM would impact the standard evaluation of FM. Presently, guidelines for FMR1 genetic testing includes early menopause, congenital intellectual disability, autism spectrum disorder, tremor or ataxia, and a family history of FXTAS or fragile X syndrome. The latter is a common cause of autism and developmental delay. Such testing is important because female carriers are at risk of having a child with fragile X syndrome.

Memantine for fragile X-associated tremor/ataxia syndrome: a randomized, double-blind, placebo-controlled trial.

OBJECTIVE: Memantine, an uncompetitive N-methyl-d-aspartate receptor antagonist, is currently approved by the US Food and Drug Administration for the treatment of moderate to severe Alzheimer's disease. Anecdotal reports have suggested that memantine may improve neurologic and cognitive symptoms of individuals with the neurodegenerative disease fragile X-associated tremor/ataxia syndrome (FXTAS); however, its efficacy and safety in this population have not been assessed in a controlled trial. METHOD: Individuals with FXTAS aged 34-80 years were enrolled in a randomized, double-blind, placebo-controlled, 1-year trial between September 2007 and August 2012. Inclusion required definite, probable, or possible FXTAS in clinical stages 1-5 according to previously published criteria. Primary outcome measures were the Behavioral Dyscontrol Scale (BDS) score and CATSYS intention tremor severity. RESULTS: Ninety-four participants were randomized from 205 screened; of those, 43 and 45 started treatment with memantine (titrated to 10 mg twice daily) and placebo, respectively. Thirty-four participants receiving memantine and 36 receiving placebo completed the 1-year endpoint assessment (n = 70). Intention-to-treat analysis showed no improvement with respect to intention tremor severity (mean [SD] values with memantine vs placebo: 1.05 [0.73] vs 1.89 [2.19], P = .047) or BDS score (16.12 [5.43] vs 15.72 [3.93], P = .727) at follow-up. Post hoc analyses of participants with early FXTAS (stage ≤ 3), those with late FXTAS (stage > 3), and those in different age groups (≤ 65 years and > 65 years) also indicated no significant improvement. More frequent mild adverse events were observed in the placebo group, while more frequent moderate adverse events occurred in the memantine group (P = .007). CONCLUSION: This randomized, double-blind, placebo-controlled trial of memantine for individuals with FXTAS showed no benefit compared to placebo with respect to the selected outcome measures. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00584948.