selective IgG deficiency disease

Selective IgG subclass deficiency is a type of immunodeficiency disorder characterized by a reduction in the level of one or more subclasses of immunoglobulin G (IgG), with normal levels of total IgG.

Definition and Classification Selectively IgG subclass deficiency is classified as a dysgammaglobulinemia, which refers to a group of disorders characterized by low or undetectable serum levels of one or more classes of immunoglobulins. This condition is typically defined as having both recurrent infections and impaired functional antibody responses.

Symptoms People with selective IgG subclass deficiency may experience various symptoms, including:

• Sinus infections and other respiratory infections
• Digestive tract infections
• Ear infections
• Pneumonia

These symptoms are often caused by the body's inability to produce sufficient antibodies to fight off infections.

Types of Selective IgG Subclass Deficiency There are four subclasses of IgG, and selective deficiencies can occur in any one of them. The most common subclass deficiency is IgG2, which primarily leads to an inadequate immune response to bacterial protein antigens.

• Selective IgG1 deficiency: This is a rare form of the condition that primarily decreases the immune response to bacterial protein antigens.
• Selective IgG2 deficiency: This is the most common subclass deficiency among children and primarily leads to an inadequate immune response to bacterial protein antigens.
• Selective IgG3 deficiency: This is less common than IgG2 deficiency and can lead to impaired immune responses to various pathogens.

Clinical Course and Prognosis The clinical course and prognosis of selective IgG subclass deficiency depend on the severity of the condition and associated morbidity. In some cases, individuals may experience recurrent infections and other complications, while in others, the condition may be relatively mild.

References

• [4] Selective IgG1 deficiency is rare and primarily decreases the immune response to bacterial protein antigens.
• [10] Selective IgG2 deficiency is the most common subclass deficiency among children and primarily leads to an inadequate immune response to bacterial protein antigens.
• [12] Deficiencies of IgG present variably according to subclass.

Common Signs and Symptoms of Selective IgG Deficiency

People with selective IgG deficiency may experience a range of symptoms, which can vary in severity and frequency. Some common signs and symptoms include:

• Recurrent Infections: Individuals with selective IgG deficiency are more prone to infections, particularly those affecting the respiratory tract, such as sinusitis, bronchitis, and pneumonia [4].
• Digestive Tract Infections: Diarrhea, abdominal pain, and other gastrointestinal issues can occur due to impaired immune function [3].
• Ear Infections: Middle ear infections are a common symptom of selective IgG deficiency [4].
• Pneumonia: Recurrent episodes of pneumonia can be a sign of underlying IgG subclass deficiency [5].
• Chronic Lung Infections: Some individuals may experience chronic lung infections, which can lead to complications such as bronchiectasis [3].

It's essential to note that not everyone with selective IgG deficiency will exhibit these symptoms. Many people may remain asymptomatic or have mild symptoms, while others may experience more severe and frequent infections.

References:

[1] Context 4 [2] Context 10 [3] Context 11 [4] Context 4 [5] Context 5

Selective IgG subclass deficiency is a condition where one or more subclasses of immunoglobulin G (IgG) are present in low levels, but the total IgG level remains normal. Diagnosing this condition can be challenging, and it often requires a combination of laboratory tests.

Blood Tests

A blood test that measures levels of immunoglobulins in the blood is typically used to diagnose selective IgG subclass deficiency. This test can detect abnormalities in the different subclasses of IgG, including IgG1, IgG2, IgG3, and IgG4 [1].

• Measurement of serum immunoglobulin levels: This involves testing for the presence of IgA, IgG, and IgM antibodies in the blood [14].
• Testing for antibody response to vaccine antigens: This test measures the body's ability to produce antibodies in response to vaccination [14].

Other Diagnostic Methods

In addition to blood tests, other methods may be used to diagnose selective IgG subclass deficiency. These include:

• Measurement of IgG subclasses: This involves testing for specific subclasses of IgG, such as IgG1, IgG2, IgG3, and IgG4 [13].
• Immunization with protein and polysaccharide antigens: This test measures the body's ability to produce antibodies in response to immunization with these types of antigens [4].

Clinical Evaluation

A clinical immunologist typically makes the diagnosis of selective IgG subclass deficiency. The specialist may carry out blood tests to:

• Measure the levels of different immunoglobulins, including IgA, IgG, and IgM
• Test for the presence of antibodies to previous immunizations or infections [15]

It's worth noting that diagnosing selective IgG subclass deficiency can be complex and often requires a combination of laboratory tests and clinical evaluation.

References:

[1] Apr 28, 2021 - Several methods are available for measuring IgG subclasses, the most common of which is enzyme-linked immunosorbent assay (ELISA) with either ...

[4] In general the diagnosis is not straightforward and involves blood tests for levels of IgG, IgA and IgM as well as immunisation with protein and polysaccharide ...

[13] Measurement of serum immunoglobulin levels. Measurement of antibody response to vaccine antigens.

[14] by AR Parker · 2017 · Cited by 43 — Measurement of IgG subclass concentrations is a standard laboratory test run as part of a panel to investigate the suspicion of antibody deficiency.

[15] A clinical immunologist usually makes the diagnosis of sIgAD. Making the diagnosis To diagnose sIgAD the specialist immunologist may carry out blood tests to: • Measure the levels of the different immunoglobulins: IgA, IgG and IgG subclasses, and IgM • Test for the presence of antibodies to previous immunisations or infections. If ...

Differential Diagnoses for Selective IgG Deficiency

Selective IgG deficiency, also known as IgG subclass deficiency, is a condition characterized by a reduction in the level of one or more subclasses of IgG. The differential diagnoses for this condition include:

• Common Variable Immunodeficiency (CVID): A primary immunodeficiency disorder that affects the production of antibodies, including IgG.
• Selective IgA Deficiency: A condition where there is an isolated deficiency of serum IgA, often associated with normal levels of IgG and IgM.
• 22q11 Microdeletion Syndrome: A genetic disorder that can lead to immunodeficiency, including selective IgG deficiency.
• HLA Class II Deficiency: A rare primary immunodeficiency disorder affecting the HLA class II region.
• Ataxia Telangiectasia (AT): A rare genetic disorder that affects the immune system and can lead to selective IgG deficiency.

These conditions should be considered in the differential diagnosis of selective IgG deficiency, as they may present with similar clinical features. [1][2][3]

Key Points

• Selective IgG deficiency is characterized by a reduction in one or more subclasses of IgG.
• Differential diagnoses include CVID, SIgAD, 22q11 microdeletion syndrome, HLA class II deficiency, and AT.
• These conditions may present with similar clinical features, such as recurrent infections and immunodeficiency.

References

[1] Knutsen AP. The diagnosis of a clinically significant IgG subclass deficiency requires evidence of antibody dysfunction in the form of recurrent infections... (Source: [5])

[2] Abrahamian F. Selective IgG3 subclass deficiency should be considered in adults with recurrent upper respiratory tract infections... (Source: [6])

[3] Agarwal S. IgG subclass deficiency is defined as a reduction in 1 or more subclasses of IgG (IgG1 and IgG2 in particular)... (Source: [7])