SNCA and Parkinson disease: Our results were shown that the ratio of oligomer/total α-synuclein decreased significantly in H&Y stage I (p = 0.001) and increased highly in H&Y II-IV stages (p = 0.037, p = 0.002, p = 0.000, respectively, Fig. 3B) compared to normal controls, which the maximum ratio of oligomeric α-synuclein appeared in the late stage of PD patients.