Quantification of LC3, p62, and TDP-43 positive fibers in the pIBM group. The percentage of LC3-positive fibers (a) was significantly higher in the pIBM group than in the PM group, but similar to the IBM group. With p62 (b), there was no statistically significant difference between the pIBM group and either the PM or IBM group. The percentage of TDP-43-positive fibers (c) was significantly lower in the pIBM group than in the IBM group, but similar to the PM group. Each subject is represented with a symbol; the open symbols indicate subjects with known IBM clinical presentation. The unbroken lines designate group medians, while the dotted lines mark 100% sensitivity and 100% specificity cutoffs for each marker (derived from the ROC analysis shown in Figure 2). **, p < 0.01; *, p < 0.05.