Premutation and full-mutation hyperexpansion of CGG-triplets in the X-linked Fragile X Mental Retardation 1 (FMR1) gene have been implicated in fragile X-associated tremor/ataxia syndrome, fragile X-associated primary ovarian insufficiency, and fragile X syndrome (FXS), respectively. The gene discussed is FMR1; the disease is fragile X syndrome.