Four key mechanisms underpin CTSB’s detrimental effects in neurodegenerative disease: (1) promoting inflammation by shifting myeloid cells to a pro-inflammatory phenotype, (2) degrading the extracellular matrix, (3) increasing mitochondrial dysfunction and oxidative stress, and (4) driving pyroptosis and apoptosis, leading to neuronal damage [1099]. The gene discussed is CTSB; the disease is neurodegenerative disease.