The analysis showed that total α-synuclein/Hb ratio effectively distinguished PSP patients from PD patients (p-value: 0.004), with an AUC of 0.853, with a sensitivity of 100% (95% CI: 63.06–100%), a specificity of 70.6% (95% CI: 41.34–88.98%), and a value of 85.06 ng/mg total α-synuclein/Hb was set as the cut-off (Figure 2). Here, GSTM1 is linked to Parkinson disease.