Since the discovery of the gene (Verkerk et al., 1991), few cases have been reported carrying unmethylated expansion > 200 CGG with no intellectual disability or a mild FXS phenotype and apparently normal levels of FMRP (Tassone et al., 2001; Pretto et al., 2013; Pretto D.I. et al., 2014). The gene discussed is FMR1; the disease is fragile X syndrome.