This potential mechanism is supported by associations between CGG repeat length and age of onset of FXTAS (Tassone et al., 2007); level of motor impairment in fXPCs (Leehey et al., 2008); negative associations of CGG repeat length with brain volume, packing density of middle cerebellar peduncle, and gray matter density of the dorsomedial frontal lobes (Cohen et al., 2006; Hashimoto et al., 2011a,b); and negative associations of both CGG repeat length and FMR1 mRNA with the connectivity strength of the superior cerebellar peduncle (Wang et al., 2013). The gene discussed is FMR1; the disease is fragile X-associated tremor/ataxia syndrome.