NUS1 and Parkinson disease: The plasma NgBR levels of the four groups were ranked from high to low as follows: PD (376.37 ± 116.03 pg/mL), PSP (319.11 ± 107.66 pg/mL), MSA (311.17 ± 96.79 pg/mL), and HC (305.94 ± 121.74 pg/mL) (Figure 3B).