Overlap Syndromes and Associated Immunoglobulin-G4-Related Liver Diseases.

Overlap syndromes (OS) are mixed hepatitic-cholestatic variants of autoimmune liver diseases (AILD), characterized by features of autoimmune hepatitis (AIH), bile duct injury, and circulating autoantibodies related to primary biliary cholangitis (PBC) or primary sclerosing cholangitis (PSC). Few cases of PBC-PSC have also been reported. Following the recognition of immunoglobulin G4-related diseases (IgG4-RD), IgG4-hepatopathy, IgG4-AIH, and PSC-with high serum IgG4-related disorders are being increasingly identified. Patients with this group of disorders often present like OS. High serum IgG4 levels in patients with PSC have been associated with worse overall survival. Hence, treatment and prognosis may differ between patients with IgG4-AIH and those with IgG4-hepatopathy. Early recognition and management of OS and related cholestatic diseases may improve outcomes and extend transplant-free survival. This review aims to formulate strategies for the diagnosis and management of OS based on current evidence. It also delves into the intricate relationship between the IgG4-related disease and AILD.