Disease associations with isolated elevations of each of the four IgG subclasses

These results confirmed some established associations between autoimmune pancreatitis, AERD, nasal polyps, and eosinophilia and elevated serum IgG4, and between monoclonal gammopathy and hepatitis C with elevated serum IgG1. It uncovered novel associations between RA and elevated IgG1 and IgG3, hypothyroidism and IBS and elevated IgG2, and between celiac disease and elevated IgG4.