FMR1 gene premutation is responsible for three groups of disorders associated with the fragile X chromosome: 1) tremor and ataxia syndrome (fragile X-primary tremor/ataxia syndrome, FXTAS) [154], 2) fragile X primary ovary insufficiency (FXPOI)—approximately 20% of women with premutation have this disorder and enter menopause before the age of 40, and all are significantly more likely to have children with fragile X syndrome (FXS) and 3) fragile X-associated neuropsychiatric disorders (FXAND). This evidence concerns the gene FMR1 and fragile X syndrome.