Selective immunoglobulin A deficiency
Encyclopedia
Selective immunoglobulin A (IgA) deficiency is a relatively mild genetic immunodeficiency
. People with this deficiency lack immunoglobulin A
(IgA), a type of antibody that protects against infections of the mucous membranes lining the mouth, airways, and digestive tract. It is defined as an undetectable serum IgA level in the presence of normal serum levels of IgG and IgM. It is the most common of the primary antibody deficiencies.
It is more common in males than in females.
Types include:
and urinary tract infections. These infections are generally mild and would not usually lead to an in-depth workup except when unusually frequent.
They may present with severe reactions including anaphylaxis
to blood transfusions or intravenous immunoglobulin
due to the presence of IgA in these blood products. When suspected, the diagnosis can be confirmed by laboratory measurement of IgA level in the blood. Patients have an increased susceptibility to pneumonia and recurrent episodes of other respiratory infections and a higher risk of developing autoimmune diseases in middle age.
Although it has some similarities to common variable immunodeficiency
, it does not present the same lymphocyte subpopulation abnormalities.
Those patients with selective immunoglobulin A deficiency may be prone to recurrent infections when on hemodialysis
.
. Of note, selective IgA deficiency can complicate the diagnosis of one such condition, celiac disease, as the deficiency masks the high levels of certain IgA antibodies usually seen in celiac disease.
As opposed to the related condition CVID
, selective IgA deficiency is not associated with an increased risk of cancer
.
Immunodeficiency
Immunodeficiency is a state in which the immune system's ability to fight infectious disease is compromised or entirely absent. Immunodeficiency may also decrease cancer immunosurveillance. Most cases of immunodeficiency are acquired but some people are born with defects in their immune system,...
. People with this deficiency lack immunoglobulin A
Immunoglobulin A
Immunoglobulin A is an antibody that plays a critical role in mucosal immunity. More IgA is produced in mucosal linings than all other types of antibody combined; between three and five grams are secreted into the intestinal lumen each day....
(IgA), a type of antibody that protects against infections of the mucous membranes lining the mouth, airways, and digestive tract. It is defined as an undetectable serum IgA level in the presence of normal serum levels of IgG and IgM. It is the most common of the primary antibody deficiencies.
Epidemiology
Prevalence varies by population, but is on the order of up to 1 in 333 people, making it relatively common for a genetic disease.It is more common in males than in females.
Pathophysiology
There is an inherited inability to produce immunoglobulin A (IgA), a part of the body's defenses against infection at the body's surfaces (mainly the surfaces of the respiratory and digestive systems). As a result, bacteria at these locations are somewhat more able to cause disease.Types include:
| Type | OMIM | Gene | Locus |
|---|---|---|---|
| IGAD1 | Unknown; MSH5 MSH5 MutS protein homolog 5 is a protein that in humans is encoded by the MSH5 gene.-Further reading:... suggested |
6p21 | |
| IGAD2 | TNFRSF13B TNFRSF13B Tumor necrosis factor receptor superfamily member 13B, also known as TNFRSF13B or more commonly as TACI, is a transmembrane receptor protein found predominantly on the surface of B cells, which are an important part of the immune system.... |
17p11 |
Symptoms and diagnosis
People with selective IgA deficiency are usually asymptomatic, but can have increased frequency of infections, particularly in the respiratory, digestive and genitourinary systems, for example, sinusitisSinusitis
Sinusitis is inflammation of the paranasal sinuses, which may be due to infection, allergy, or autoimmune issues. Most cases are due to a viral infection and resolve over the course of 10 days...
and urinary tract infections. These infections are generally mild and would not usually lead to an in-depth workup except when unusually frequent.
They may present with severe reactions including anaphylaxis
Anaphylaxis
Anaphylaxis is defined as "a serious allergic reaction that is rapid in onset and may cause death". It typically results in a number of symptoms including throat swelling, an itchy rash, and low blood pressure...
to blood transfusions or intravenous immunoglobulin
Intravenous immunoglobulin
Intravenous immunoglobulin is a blood product administered intravenously. It contains the pooled IgG extracted from the plasma of over one thousand blood donors. IVIG's effects last between 2 weeks and 3 months...
due to the presence of IgA in these blood products. When suspected, the diagnosis can be confirmed by laboratory measurement of IgA level in the blood. Patients have an increased susceptibility to pneumonia and recurrent episodes of other respiratory infections and a higher risk of developing autoimmune diseases in middle age.
Although it has some similarities to common variable immunodeficiency
Common variable immunodeficiency
Common variable immunodeficiency is a group of approximately 150 primary immunodeficiencies , which have a common set of symptoms but which have different underlying causes.Common variable immunodeficiency is the most commonly encountered primary immunodeficiency.-Causes and types:CVID...
, it does not present the same lymphocyte subpopulation abnormalities.
Those patients with selective immunoglobulin A deficiency may be prone to recurrent infections when on hemodialysis
Hemodialysis
In medicine, hemodialysis is a method for removing waste products such as creatinine and urea, as well as free water from the blood when the kidneys are in renal failure. Hemodialysis is one of three renal replacement therapies .Hemodialysis can be an outpatient or inpatient therapy...
.
Treatment
The treatment consists of identification of comorbid conditions, preventive measures to reduce the risk of infection, and prompt and effective treatment of infections. Infections in an IgA-deficient person are treated as usual (i.e., with antibiotics). There is no treatment for the underlying disorder.Prognosis
Prognosis is excellent, although there is an association with autoimmune diseaseAutoimmune disease
Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. In other words, the body actually attacks its own cells. The immune system mistakes some part of the body as a pathogen and attacks it. This may be restricted to...
. Of note, selective IgA deficiency can complicate the diagnosis of one such condition, celiac disease, as the deficiency masks the high levels of certain IgA antibodies usually seen in celiac disease.
As opposed to the related condition CVID
Cvid
Cvid stands for*Common variable immunodeficiencyand is also used to refer to the video codec Compact Video or*Cinepak*Cvid also stands for Dollar...
, selective IgA deficiency is not associated with an increased risk of cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
.