The goal of the study is to identify and characterize a potential neurophysiological biomarker for early stage FXTAS and for disease progression by evaluating the electrophysiological activity in both asymptomatic FMR1 Premutation carriers and in patients with various stages (duration) of FXTAS. Additionally correlations will be studied between these BNA data and demographics (gender, age and disease duration). length of the pathological CGG repeat expansion as well as FXTAS score, gait and posture abnormalities (obtained by instrumental timed up and go evaluation) and neuropsychological status.