Autoimmunity has been considered the most probable pathogenesis of IgG4-RD [16] and several autoantigens have been suggested, including lactoferrin [17], carbonic anhydrase II (CAII) [18], amylase-alpha 2A [19], pancreatic secretory trypsin inhibitor (PSTI) [20] and plasminogen-binding protein peptide [21], with autoantibodies against these targets successfully examined in patients with IgG4-RD in laboratories. Here, CA2 is linked to immunoglobulin G4-related sclerosing disease.