FMR1 and fragile X-associated tremor/ataxia syndrome: From a molecular point of view, in patients with FXTAS, the FMRP (fragile X mental retardation protein) amount is normal, while the FMR1 mRNA level is drastically elevated in the brain and in leukocytes [167], leading to toxicity (through the production of FRMpolyG by repeat-associated non-AUG (RAN) translation) and causing the cellular injury responsible for the symptoms (intranuclear inclusions and DNA damage through R-loops formation) [163].