Further evaluation of the differences in DAT and CSF protein levels at baseline indicated that only the PD‐OD group had a larger dopaminergic deficit in the caudate (P = 0.007 and P = 0.021) and putamen (P = 0.024 and P = 0.011) than the PD group, as shown in Table 2. The gene discussed is SLC6A3; the disease is Parkinson disease.