Common variable immunodeficiency
| Common variable immunodeficiency | |
|---|---|
| Classification and external resources | |
| Specialty | hematology |
| ICD-10 | D83 |
| ICD-9-CM | 279.06 |
| OMIM | 240500 |
| DiseasesDB | 3274 |
| eMedicine | ped/444 derm/870 |
| Patient UK | Common variable immunodeficiency |
| MeSH | D017074 |
Common variable immunodeficiency (CVID) is an immune disorder characterized by recurrent infections and low antibody levels, specifically in immunoglobulin (Ig) types IgG, IgM and IgA. Generally symptoms include high susceptibility to foreign invaders, , and inflammation and infection of the gastrointestinal tract. However, symptoms vary greatly between people. CVID is a lifelong disease.
The origins of CVID is poorly understood. Current research points to deletions in particular genetic markers encoding cell surface proteins and cytokine receptors, such as CD19, CD20, CD21, and CD80, as a likely cause. A deletion is a mutation in which part of the chromosome is lost during DNA replication. Additionally, the disease is defined by T cell defects, namely reduced proliferative capacity. The disease is hard to diagnose, taking on average 6–7 years after onset. CVID is a primary immunodeficiency.
Treatment options are limited, and usually include lifelong immunoglobulin replacement therapy. This therapy is thought to help reduce bacterial infections. This treatment alone is not wholly effective, and many people still experience other symptoms like lung disease and noninfectious inflammatory symptoms.
CVID was first diagnosed over 60 years ago, and since has emerged as the predominant class of primary antibody deficiencies. CVID is formally diagnosed by levels of IgG and IgA more than two standard deviations from the norm, and no other cause for hypogammaglobulinemia, an abnormally low level of immunoglobulins in the blood. It is thought to affect between 1 in 25,000 to 1 in 50,000 people worldwide.
The symptoms of CVID vary between people affected. Its main features are hypogammaglobulinemia and recurrent infections. Hypogammaglobulinemia manifests as a significant decrease in the levels of IgG antibodies, usually alongside IgA antibodies; IgM antibody levels are also decreased in about half of people. Infections are a direct result of the low antibody levels in the circulation, which do not adequately protect them against pathogens. The microorganisms that most frequently cause infections in CVID are bacteria Haemophilus influenzae, and Staphylococcus aureus. Pathogens less often isolated from people include Neisseria meningitidis, Pseudomonas aeruginosa and Giardia lamblia. Infections mostly affect the respiratory tract (nose, sinuses, bronchi, lungs) and the ears; they can also occur at other sites, such as the eyes, skin and gastrointestinal tract. These infections respond to antibiotics but can recur upon discontinuation of antibiotics. Bronchiectasis can develop when severe, recurrent pulmonary infections are left untreated.
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