The main laboratory changes in IgG4-RD are (1) normocytic–normochromic anemia with eosinophilia; (2) increase in immunoglobulin levels such as IgG and IgG4, with (3) polyclonal peak in serum protein electrophoresis; (4) increase in C-reactive protein (CRP) and erythrocyte sedimentation volume; (5) when certain organs are affected, an increase in alkaline phosphatase, gamma-glutamyl transferase (in autoimmune pancreatitis and primary sclerosing cholangitis), salivary amylase (in parotitis) and complement consumption (C3 and C4) may be seen in renal dysfunction [1,2,3,4,5]. The gene discussed is C4A; the disease is parotitis.