Perspective: evolving concepts in the diagnosis and understanding of common variable immunodeficiency disorders CVID.
Clinic Rev Allerg Immunol. Common variable immunodeficiency - an update. Saikia B, Gupta S. Common variable immunodeficiency. Indian J Pediatr. Cleveland Clinic. Updated July 8, Cunningham-Rundles C. The many faces of common variable immunodeficiency. New diagnostic criteria for common variable immune deficiency CVID , which may assist with decisions to treat with intravenous or subcutaneous immunoglobulin. Clin Exp Immunol.
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Table of Contents View All. Table of Contents. Physical Examination. Laboratory Tests. Differential Diagnosis. CVID is estimated to affect 1 in 25, to 1 in 50, people worldwide, although the prevalence can vary across different populations. The cause in CVID is unknown in approximately 90 percent of cases. It is likely that this condition is caused by both environmental and genetic factors. While the specific environmental factors are unclear, the genetic influences in CVID are believed to be mutations in genes that are involved in the development and function of immune system cells called B cells.
B cells are specialized white blood cells that help protect the body against infection. When B cells mature, they produce special proteins called antibodies also known as immunoglobulins. These proteins attach to foreign particles, marking them for destruction.
Mutations in the genes associated with CVID result in dysfunctional B cells that cannot make sufficient amounts of antibodies. In about 10 percent of cases, a genetic cause for CVID is known. Mutations in at least 13 genes have been associated with CVID. The protein produced from this gene plays a role in the survival and maturation of B cells and in the production of antibodies.
Other genes associated with CVID are also involved in the function and maturation of immune system cells, particularly of B cells; mutations in these genes account for only a small percentage of cases. All individuals with CVID have a shortage deficiency of two or three specific antibodies. A shortage of these antibodies makes it difficult for people with this disorder to fight off infections. Abnormal and deficient immune responses over time likely contribute to the increased cancer risk. In addition, vaccines for diseases such as measles and influenza do not provide protection for people with CVID because they cannot produce an antibody response.
Most cases of CVID are sporadic and occur in people with no apparent history of the disorder in their family. These cases probably result from a complex interaction of environmental and genetic factors. Only a few of these defects have been identified, and the cause of most cases of CVID is unknown.
CVID is also linked to IgA deficiency, a related condition in which only the level of the antibody immunoglobulin A IgA is low, while levels of other antibody types are usually normal or near normal.
People with CVID may experience frequent bacterial and viral infections of the upper airway, sinuses, and lungs. Acute lung infections can cause pneumonia, and long-term lung infections may cause a chronic form of bronchitis known as bronchiectasis, which is characterized by thickened airway walls colonized by bacteria.
People with CVID also may have diarrhea, problems absorbing food nutrients, reduced liver function, and impaired blood flow to the liver. Autoimmune problems that cause reduced levels of blood cells or platelets also may occur. People with CVID may develop an enlarged spleen and swollen glands or lymph nodes, as well as painful swollen joints in the knee, ankle, elbow, or wrist.
In addition, people with CVID may have an increased risk of developing some cancers. While CVID is thought to be due to genetic defects, the exact cause of the disorder is unknown in the large majority of cases. In still others there are defects of the T-cells, and this may also contribute to increased susceptibility to infections as well as autoimmunity, granulomata and tumors.
To be sure that CVID is the correct diagnosis, there must be evidence of a lack of functional antibodies and other possible causes of these immunologic abnormalities must be excluded. Patients with CVID also have an increased incidence of autoimmune or inflammatory manifestations, granulomata and an increased susceptibility to cancer when compared to the general population.
Sometimes it is the presence of one of these other conditions that prompts an evaluation for CVID. The medical terms for absent or low blood immunoglobulins are agammaglobulinemia and hypogammaglobulinemia, respectively. It is a place where people affected by CVID can network, ask questions, and share insights and experiences. Both males and females may have CVID.
In the majority, the diagnosis is not made until the third or fourth decade of life. Because the immune system is slow to mature, the diagnosis of CVID is generally not made until after the age of 4.
The usual presenting features of CVID are recurrent infections involving the ears, nasal sinuses, bronchi breathing tubes and lungs respiratory tract. When the lung infections are severe and occur repeatedly, permanent damage with widening and scarring of the bronchial tree, a condition termed bronchiectasis, may develop.
The organisms commonly found in these sinopulmonary infections are bacteria that are widespread in the population and that often cause pneumonia Hemophilus influenzae, pneumococci, and staphylococci even in people who do not have CVID. The purpose of treatment of lung infections is to prevent their recurrence and the accompanying chronic and progressive damage to lung tissue. A regular cough in the morning and the production of yellow or green sputum may suggest the presence of chronic bronchitis or bronchiectasis.
Patients with CVID may also develop enlarged lymph nodes in the neck, the chest or abdomen. The specific cause is unknown, but enlarged lymph nodes may be caused by infection, an abnormal immune response or both. In some cases, other collections of inflammatory cells, called granulomas, can be found in lungs, lymph nodes, liver, skin or other organs. These are largely composed of cells called monocytes and macrophages. They may be a response to an infection, but the cause is not really known.
Although patients with CVID have depressed antibody responses and low levels of immunoglobulins in their blood, some of the antibodies that are produced by these patients may attack their own tissues autoantibodies. These autoantibodies may attack and destroy blood cells, like red cells, white cells or platelets. Autoantibodies may also cause other diseases such as arthritis or endocrine disorders, like thyroid disease.
Gastrointestinal complaints such as abdominal pain, bloating, nausea, vomiting, diarrhea and weight loss are not uncommon in CVID.
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