Repeat expansions falling between a typical CGG repeat count and 200 repeats (i.e., 55 – 200 CGG repeats) on the FMR1 gene result in a premutation, which is associated with increased FMR1 mRNA accompanied by minor reduction in protein levels, but which is not associated with the full cognitive and behavioral presentation of FXS (Fu et al., 1991; Wheeler et al., 2014). The gene discussed is FMR1; the disease is fragile X syndrome.