FMR1 and fragile X-associated tremor/ataxia syndrome: Along with the presence of FMR1 mRNA in ubiquitin-positive intranuclear inclusions of FXTAS patient brains, these observations point to a toxic RNA gain-of-function mechanism for FXTAS pathogenesis, which could lead to sequestration of various rCGG repeat-binding proteins (Tassone et al., 2004).