Objective: To report pain and other non-motor symptoms in patients with FXTAS.

Background: Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS) is a neurodegenerative disorder caused by CGG repeat expansion in the premutation range (55-200) in the Fragile X mental retardation 1 gene (FMR1). 
Along with common motor signs of ataxia, tremor and parkinsonism there are prominent non-motor symptoms including neuropsychiatric, autonomic, sleep and executive dysfunction, peripheral neuropathy, fibromyalgia, musculoskeletal pain and migraine.   
Smaller expansions (41-54 repeats) in the FMR1 gene termed  “gray zone” alleles had phenotypes similar to those in premutation carriers.

Method: Case series report and literature review.

Results: We would like to present clinical, genetic, radiologic and electrophysiological findings in our series of patients with FMR1 gene premutation and gray zone range seen at our clinic.  8 patients met criteria for FXTAS: 6 males and 2 females; 3 had CGG repeats in the “gray zone” range. 
Over their clinical course, pain occurred in most patients, including neuropathic as well as musculoskeletal (including back) pain.  Pain was present at different stages, frequently prodromal and throughout the duration of disease. 
EMG-NCS was normal in all tested patients, suggesting small fiber neuropathy that may also contribute to autonomic dysfunction. Punch skin biopsy to evaluate for small fiber neuropathy was declined. 
Treatment of neuropathic pain in our patients included tricyclic antidepressants, gabapentinoids, and physical therapy. 
One male patient was treated with deep brain stimulation (DBS), which did not improve his chronic pain. 
Several mechanisms of pain can be found in patients with FXTAS and gray zone premutations including musculoskeletal, back pain and neuropathic pain. Neuropathic pain can be considered as central as well as due to small fiber neuropathy.

Conclusion: FXTAS and FMR1 gene premutation disorders are multisystem, multiorgan neurodegenerative disorders in which pain can be refractory and can seriously affect quality of life.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/pain-and-non-motor-symptoms-in-fxtas/