AUTHOR=Hagerman Randi J. , Protic Dragana , Rajaratnam Akash , Salcedo-Arellano Maria J. , Aydin Elber Yuksel , Schneider Andrea TITLE=Fragile X-Associated Neuropsychiatric Disorders (FXAND) JOURNAL=Frontiers in Psychiatry VOLUME=9 YEAR=2018 URL=https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2018.00564 DOI=10.3389/fpsyt.2018.00564 ISSN=1664-0640 ABSTRACT=

Fragile X syndrome (FXS) is caused by the full mutation (>200 CGG repeats) in the Fragile X Mental Retardation 1 (FMR1) gene. It is the most common inherited cause of intellectual disability (ID) and autism. This review focuses on neuropsychiatric disorders frequently experienced by premutation carriers with 55 to 200 CGG repeats and the pathophysiology involves elevated FMR1 mRNA levels, which is different from the absence or deficiency of fragile X mental retardation protein (FMRP) seen in FXS. Neuropsychiatric disorders are the most common problems associated with the premutation, and they affect approximately 50% of individuals with 55 to 200 CGG repeats in the FMR1 gene. Neuropsychiatric disorders in children with the premutation include anxiety, ADHD, social deficits, or autism spectrum disorders (ASD). In adults with the premutation, anxiety and depression are the most common problems, although obsessive compulsive disorder, ADHD, and substance abuse are also common. These problems are often exacerbated by chronic fatigue, chronic pain, fibromyalgia, autoimmune disorders and sleep problems, which are also associated with the premutation. Here we review the clinical studies, neuropathology and molecular underpinnings of RNA toxicity associated with the premutation. We also propose the name Fragile X-associated Neuropsychiatric Disorders (FXAND) in an effort to promote research and the use of fragile X DNA testing to enhance recognition and treatment for these disorders.