CTSS and autoimmune disease: Cathepsins, a family of proteolytic enzymes belonging to the lysosomal cysteine protease group, are essential for protein degradation, antigen presentation, and apoptosis.[6,7] These enzymes are implicated in various physiological and pathological processes, including cancer, autoimmune diseases, cardiovascular diseases, and neurodegenerative disorders.[8,9] Recent evidence suggests that cathepsins play critical roles in muscle metabolism and function, with direct relevance to sarcopenia.