Agammaglobulinemia is a group of inherited immune deficiencies characterized by a low concentration of antibodies in the blood due to the lack of particular lymphocytes in the blood and lymph. Antibodies are proteins (immunoglobulins, (IgM), (IgG) etc) that are critical and key components of the immune system. They are essential if the immune system is to do its job of fighting off bacteria, viruses, and other foreign substances that threaten the body. The specialized precursor cells that produce gammaglobulins, fail to develop or function properly leading to the deficiency in the number of mature lymphocyte cells called B cells.
The types of agammaglobulinemia are: X-linked agammaglobulinemia (XLA), the much rarer X-linked agammaglobulinemia with growth hormone deficiency (about 10 cases reported), and autosomal recessive agammaglobulinemia (ARAG). All of these disorders are characterized by a weakened immune system that must be strengthened by the administration of gammaglobulin in order to fight off infections.