Heavy chain disease is a form of paraproteinemia and plasma cell dyscrasia that involves the proliferation of cells producing immunoglobulin heavy chains.This disease is characterized by an excessive production of heavy chains that are short and truncated. These heavy chain disease proteins have various deletions, mainly in their amino-terminal part, which causes the heavy chains to lose the ability to form disulfide bonds with the light chains. The defect in the immunoglobulins presumably arises during somatic hypermutation. Deletion of the N-terminal part of the heavy chain disease protein leads to aggregation and signaling of the B cell receptor, presumably due to the loss of the anti-aggregating properties of the light chain. Classification
There are four forms:

alpha chain disease (Seligmanns disease)
gamma chain disease (Franklins disease)
mu chain disease
delta chain disease

IgA/αHCD
The most common type of heavy chain disease is the IgA type, known as αHCD. The most common type of αHCD is the gastrointestinal form (known as immunoproliferative small intestine disease or IPSID), but it has also been reported in the respiratory tract, and other areas of the body. IgG/γHCD
Franklins disease (gamma heavy chain disease)
It is a very rare B-cell lymphoplasma cell proliferative disorder which may be associated with autoimmune diseases and infection is a common characteristic of the disease. It is characterized by lymphadenopathy, fever, anemia, malaise, hepatosplenomegaly, and weakness. The most distinctive symptom is palatal edema, caused by nodal involvement of Waldeyers ring. Diagnosis is made by the demonstration of an anomalous serum M component that reacts with anti-IgG but not anti-light chain reagents.
Diagnosis
Treatment
Treatment is symptomatic, often addressing indicators associated with peripheral pulmonary artery stenosis. Laryngotracheal calcification resulting in dyspnea and forceful breathing can be treated with bronchodilators including the short and long-acting β2-agonists, and various anticholinergics. Prognosis
Prognosis is  good, yet life expectancy depends on the severity and extent of diffuse pulmonary and arterial calcification. History
Keutel Syndrom was first described by the pediatric Cardiologist Jürgen Keutel and Colleagues in 1972 in Göttingen, Germany. References
External links
Keutel syndrome at NIHs Office of Rare Diseases