A. Bar graph showing expression of MPO gene in different human brain cells in published brain single cell RNA sequencing database (https://www.brainrnaseq.org). B. Representative confocal images of brain tissues from non-ALS patients, SOD1-type ALS patients, and C9orf72-type ALS patients immunostained for MPO. Scale bar is 28 μm C. Quantification of fractions of MPO+ cells showing significantly more MPO+ cells in SOD1-type ALS patients’ primary motor cortex. D. Representative confocal images showing brain tissues from non-ALS patients, SOD1-type ALS patients, and C9orf72-type ALS patients immunostained for MPO and CEP. Scale bar is 14 μm. E. Quantification of fractions of MPO+CEP+ cells revealing significantly more MPO+CEP+ cells in SOD1-type ALS patients’ primary motor cortex. All data are mean ± s.e.m. Comparisons between groups were made using one-way ANOVA followed by Tukey’s post hoc test. * p < 0.05, ** p < 0.01, and *** p < 0.001. MPO, myeloperoxidase. ns, not significant.