Heavy chain diseases are a group of rare disorders characterized by the abnormal production and secretion of monoclonal immunoglobulin heavy chains. Immunoglobulins, also known as antibodies, are proteins produced by the immune system to fight off foreign substances in the body. The heavy chain is a component of the immunoglobulin molecule responsible for its structural stability and binding to antigens.
In heavy chain diseases, the abnormal heavy chains are produced as a result of genetic mutations or other unknown factors. These mutated heavy chains are faulty in structure and function, leading to their abnormal accumulation and secretion by immune cells called plasma cells.
There are three main types of heavy chain diseases: alpha-heavy chain disease (α-HCD), gamma-heavy chain disease (γ-HCD), and mu-heavy chain disease (µ-HCD). Each type is characterized by the production of abnormal heavy chains of a specific immunoglobulin class.
Symptoms of heavy chain diseases may vary depending on the affected organ system, but common features include weakness, fatigue, recurrent infections, weight loss, and enlarged lymph nodes or spleen. Diagnosis usually involves blood tests and tissue biopsies to detect the abnormal heavy chains.
Treatment options for heavy chain diseases are limited and depend on the specific type and the extent of the disease. They may include chemotherapy, immunosuppressive drugs, and sometimes stem cell transplantation. Management aims to control symptoms, suppress the abnormal heavy chain production, and improve the patient's quality of life.
