Heavy Chain Diseases

Heavy chain diseases are plasma cell cancers in which a clone of plasma cells produces a large quantity of pieces of abnormal antibodies called heavy chains.

Heavy chain diseases are categorized according to the type of heavy chain produced: alpha, gamma, or mu.

Alpha heavy chain disease affects mainly younger adults of Middle Eastern or Mediterranean ancestry. Infiltration of the intestinal tract wall by cancerous plasma cells often prevents proper absorption of nutrients from food (malabsorption), resulting in severe diarrhea and weight loss. Alpha heavy chain disease progresses rapidly, and half of the affected people die within 1 year. Treatment with cyclophosphamide, prednisone (a corticosteroid), and antibiotics may slow the progression of the disease.

Gamma heavy chain disease affects mainly older adults. Some people with gamma heavy chain disease have no symptoms. Infiltration of the bone marrow by cancerous plasma cells causes other people to have symptoms of recurring infections, such as repeated episodes of fever and chills associated with a decreased number of white blood cells, and fatigue and weakness associated with severe anemia. Cancerous plasma cells may also enlarge the liver and spleen. People with symptoms may respond to therapy with cyclophosphamide and prednisone.

Mu heavy chain disease, the rarest of the three heavy chain diseases, may cause enlargement of the liver and spleen as well as enlargement of the lymph nodes in the abdomen. Length of survival and response to chemotherapy drugs vary widely.