These evidences suggest that the increased level of cystatin C determined in PBCp group may represent a physiological protective mechanism against exacerbated expression of CTSS following immunological disorders, even if the heterogeneity of patients in terms of clinical parameters, grade of liver inflammation and stage of liver fibrosis and therapies, together with the transversal nature of the study, did not allow to demonstrate the causal link of these proteins to PBC. This evidence concerns the gene CST3 and primary biliary cholangitis.