Progressive myoclonus epilepsy EPM1 is a rare neurodegenerative disorder resulting from the partial loss of function of cystatin B (CSTB), a cysteine protease inhibitor with neuroprotective roles. The disease's mechanisms are not fully understood, and no treatments exist to manage the severe myoclonus associated with EPM1. Analyses of proteome and transcriptome data in CSTB-deficient (Cstb-/-) mouse brains—specifically the cerebellum, cerebral cortex, and hippocampus—during disease progression revealed three critical pathways as potential therapeutic targets: 1) an upregulation of immune response genes indicating increased immune activity across all brain regions, 2) a downregulation of the oxidative phosphorylation pathway suggesting impaired energy metabolism, and 3) lysosomal dysfunction, evidenced by upregulated genes necessary for lysosomal function and downregulated genes for lysosomal acidification. Additionally, clusterin, apolipoprotein E, peroxiredoxin 6, cathepsin D, and aldolase C were identified as potential biomarkers for disease progression.