heavy chain disease [AS, heafig + L, catena, chain; dis, opposite of; Fr, aise, ease] , a plasma cell disorder characterized by a proliferation of immunoglobulin heavy chains. Excessive levels of alpha, gamma, delta, and mu chains are produced, and effects tend to vary according to the predominant type of heavy chain. Alpha heavy chain disease mainly affects children living in the Middle East, causing diffuse abdominal lymphoma and malabsorption disorders. Most gamma heavy chain disease patients are elderly men who have symptoms resembling those of malignant lymphoma: enlarged liver and spleen, fever, anemia, and increased susceptibility to infections. Delta heavy chain disease is rare and marked by symptoms similar to those of multiple myeloma. Mu heavy chain disease presents symptoms of chronic lymphocytic leukemia, and treatment is symptomatic.
