Fig. 3. SOD1 aggregates in the PD brain have an altered Cu : Zn ratio suggestive of impaired Cu binding. SOD1 aggregate identified with (A) immunohistochemistry using anti-SOD1 (B8H10), (B) ptychography and (C–E) and XFM. SOD1 aggregates were analyzed for deviation in Cu : Zn ratio from a hypothetical mean 1 : 1 stoichiometry of holo-SOD1 dimers. (F and G) At true pixel size of 80 nm there was a strong positive spatial correlation between Cu and Zn within SOD1 aggregates but not in neuropil (NP). (H) A highly specific 26% decrease in Cu : Zn (W = −276; 95% confidence interval −0.288, −0.165; Wilcoxon signed rank test) was observed in the analyzed population of SOD1 aggregates. Representative images from scan IDs fly26 (SOD1). Scale bars = 1 μm. Structures were sampled from 6–7 PD cases with multiple structures sampled from each case where time was allowed. Total structures analysed; nLB = 8, nSOD1 = 23 nNM = 6, nNP = 32. Box-plot graph depicts the median and quartile values as the central line and box boundaries. Whiskers represent min to max values. *p < 0.05, **p < 0.01, ***p < 0.001 based on Kruskal–Wallis (two-sided).