<unk>  is a form of dysgammaglobulinemia where the proportional levels of the<unk>  isotype are reduced relative to other immunoglobulin isotypes.<unk>  is often found in children as transient hypogammaglobulinemia of infancy (THI), which may occur with or without additional decreases in IgA or IgM.<unk>  has four subclasses:<unk> 1,<unk> 2,<unk> 3, and<unk> 4. It is possible to have either a global<unk> , or a deficiency of one or more specific subclasses of<unk> . The main clinically relevant form of<unk>  is<unk> 2.<unk>  is not usually encountered without other concomitant immunoglobulin deficiencies, and<unk>  is very common but usually asymptomatic.<unk> 1 is present in the bloodstream at a percentage of about 60-70%,<unk> 2-20-30%,<unk> 3 about 5-8 %, and<unk> 4 1-3 %.<unk>  subclass deficiencies affect only<unk>  subclasses (usually<unk> 2 or<unk> 3), with normal total<unk>  and IgM immunoglobulins and other components of the immune system being at normal levels. These deficiencies can affect only one subclass or involve an association of two subclasses, such as<unk> 2 and<unk> 4.<unk> es are usually not diagnosed until the age of 10. Some of the<unk>  levels in the blood are undetectable and have a low percentage such as<unk> 4, which makes it hard to determine if a deficiency is actually present.<unk>  subclass deficiencies are sometimes correlated with bad responses to pneumoccal polysaccharides, especially<unk> 2 and or<unk> . Some of these deficiencies are also involved with pancreatitis and have been linked to<unk> 4 levels.
IgG deficiency
T cell deficiency
Primary immunodeficiency
Selective immunoglobulin A deficiency
Complement deficiency
Combined immunodeficiencies
Isolated primary immunoglobulin M deficiency
Leukocyte adhesion deficiency