This increased FMR1-mRNA level, coupled with studies revealing the presence of the expanded FMR1-mRNA inside intranuclear inclusions in patient materials (Greco et al., 2002; Tassone et al., 2004; Iwahashi et al., 2006), led to the development of an RNA-gain-of-function hypothesis for the FXTAS pathogenesis (reviewed in Hagerman and Hagerman, 2004). The gene discussed is FMR1; the disease is fragile X-associated tremor/ataxia syndrome.