A variety of disorders have been associated with mutations in the fragile X mental retardation 1 (FMR1) gene, including fragile X syndrome (FXS) caused by a full mutation (>200 CGG repeats in the 5′ untranslated region of the FMR1 gene) leading to absence or deficiency of the FMR1 protein (FMRP) and premutation (55−200 CGG repeats) disorders characterized by elevations in FMR1 mRNA to 2−8 times the normal level (Lozano et al., 2014). The gene discussed is FMR1; the disease is fragile X syndrome.