Author: Brian Wu PhD. MD Candidate, Keck School of Medicine, Los Angeles, USA; Chief Editor: Dr Amanda Oakley, Dermatologist, Hamilton, New Zealand, September 2015.
IgG or immunoglobulin G is the most prevalent form of antibody. Antibodies are small proteins produced by plasma cells. They are essential part of the humoral or circulating immune system.
IgG is composed of 4 peptide chains: 2 heavy chains and 2 light chains. There are 4 subclasses of IgG.
Patients with IgG deficiency have a normal total level of IgG but low levels of at least one of the IgG subclasses. Each of these subclasses has a slightly different immune function:
In patients with IgG subclass deficiency, other components of the immune system function normally.
Thepattern of inheritance connected with this disorder is not known. IgG subclass deficiency can affect both males and females. However, partial gene deletions have been discovered in some patients with selective IgA deficiency.
Patients with IgG subclass deficiency may present with:
Diagnosis of IgG subclass deficiency is largely made on patient medical history and physical exam. IgG subclasses can be measured but the results of this testing are not always conclusive. Levels should be tested again in several months to determine if the values are truly abnormal.
Diagnosis should also take into account the patient’s overall health, presenting symptoms, and response to vaccines.
IgG subclass deficiency is treated with:
A patient with a specific antibody deficiency lacks the ability to produce IgG molecules, which play a vital role in the body’s immune defense system. Specific antibody deficiency is also called partial antibody deficiency or impaired polysaccharide responsiveness.
The exact cause of specific antibody deficiency is not known. It is speculated that it is due to a breakdown in communication between B cells and other cells in the immune system.
Some patients with specific antibody deficiency are asymptomatic because other components of their immune system are still functional. Other patients may present with:
The diagnosis of specific antibody deficiency is based on:
Treatment for specific antibody deficiency centres on:
Main goals of treatment are to prevent bronchiectasis and scarring in the lungs from repeated respiratory infections and to maintain overall quality of life.
The prognosis for patients with specific antibody deficiency is generally good. Children have been known to outgrow specific antibody deficiency naturally and those who do not are still able to maintain good quality of life with antibiotic and/or immunoglobulin therapy.
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