FMR1 and fragile X-associated tremor/ataxia syndrome: The premutation leads to enhanced levels of FMR1 mRNA from 2 to 8 times normal and the excess mRNA causes RNA toxicity including the sequestration of proteins important for neuronal function, oxidative stress, and mitochondrial dysfunction that eventually can lead to the fragile X-associated tremor ataxia syndrome (FXTAS) (1).