Reduced density of striatal dopamine transporter (DAT) is a molecular characteristic linked to nigrostriatal dysfunction, which is observed with varying degrees of severity in patients with FXTAS [23,24] and Parkinson’s Disease (PD), and serves as an alternative diagnostic criterion for PD [25,26,27,28]. Here, SLC6A3 is linked to fragile X-associated tremor/ataxia syndrome.