An immunologic classification of pernicious anemia.

Addisonian pernicious anemia (PA) usually develops after age 50. These PA patients are immunocompetent and usually manifest gastric autoimmunity. The prevalence of PA is increased about 10-fold with multiple myeloma and 250-fold in adults with primary immunoglobulin deficiency. Atrophic gastritis develops at an unusually early age with primary immunoglobulin deficiency but not with myeloma. Family history with myeloma is often relevant to PA. Atrophic gastritis develops in both syndromes without gastrict autoantibody production.