FMR1 and fragile X-associated tremor/ataxia syndrome: The normal number of CGG of FMR1 is less than 45 CGG repeats in the 5′ UTR region,gray zone contains 46–54 repeats (carriers with either movement disorders or memory complaints), premutation contains 55–200 repeats (causes FXTAS or FXPOI) and full mutation > 200(causes Fragile X syndrome).