Fig. 1

CHCHD2 mRNA and protein expression was reduced in erythrocytes of PD patients. a Genes associated with PD or atypical Parkinsonism in pooled erythrocyte samples from controls and PD patients at various stages were analyzed by the NanoString multiplex gene expression method. The samples were pooled according to Additional file 1: Table S1 [four comparison groups (n = 12 each) with each pooled into three sub-groups]. Ten genes were analyzed following removal of low expression genes. Significantly decreased CHCHD2 mRNA was detected in all PD groups compared to the control group [F (3, 4) = 52.0, one-way ANOVA, n = 3; p < 0.01 for Early or Mid PD vs. control, p < 0.001 for Late PD vs. control]. b Validation of the discovery cohort by ddPCR in the discovery set also identified decreased CHCHD2 mRNA in erythrocytes of all PD groups [F(3, 8) = 20.80, one-way ANOVA, n = 3; p < 0.01 or 0.001 for each PD group vs. the controls] compared to controls. No difference in CHCHD2 mRNA expression was observed between PD groups by Tukey’s multiple comparisons test. Left: Original representative ddPCR picture. FAM channel (Axis X) indicates CHCHD2, VIC channel (Axis Y) indicates AHSP. Right: Statistical result. c Decreased CHCHD2 protein in erythrocytes of PD patients. Proteins were extracted from pooled erythrocytes of the same cohort as used in the NanoString and ddPCR studies. Compared to controls, CHCHD2 was decreased significantly from 1.01 ± 0.07 to 0.43 ± 0.12 (p < 0.05, Mann–Whitney U test, n = 3)