SLC6A3 and spinocerebellar ataxia type 31: The present study analyzed five cases of SCA31 with nigrostriatal dopaminergic dysfunction (NSDD), defined as the presence of at least two of the three cardinal motor symptoms of Parkinson’s disease (PD), including resting tremor, rigidity, and bradykinesia/akinesia or one of the three cardinal motor symptoms plus an abnormal 123I-ioflupane dopamine transporter (DAT) scintigraphy finding.