Common variable immunodeficiency (CVID), also called hypogammaglobulinemia or adult-onset hypogammaglobulinemia, is a relatively common primary immune deficiency. The disorder is characterized by a lack of antibody-producing B-cells or plasma cells, low levels of most or all immunoglobulin isotypes and recurrent bacterial infections.
CVID is considered the most prevalent type of primary immunodeficiency. Primary immunodeficiencies are disorders that occur because part of the body's immune system does not function properly. Unlike secondary immunodeficiencies, which are caused by factors (like viruses or chemotherapy) outside of the immune system, primary immunodeficiencies are caused by intrinsic or genetic defects in the immune system.
While the exact incidence rate of CVID is unknown, researchers estimate that about one out of 50,000 individuals develop the disorder. Most patients develop the disorder between the ages of 20 and 50. Only about 20% of patients are diagnosed during childhood. CVID affects an equal number of males and females.
CVID is diverse, both in its clinical presentation (signs and symptoms) and in the types of deficiency. Although decreased serum levels of immunoglobulin G (IgG) and immunoglobulin A (IgA) are characteristic of the disorder, about half of CVID patients also have decreased immunoglobulin M (IgM) levels in the blood. In addition, about half of CVID patients experience some T-lymphocyte dysfunction.
The first signs of the deficiency are recurrent bacterial infections, which may occur as early as infancy or as late as the fourth decade of life.
Because of the variable manifestations of CVID, no clear pattern of inheritance has been established. In most cases, there is no family history of immunodeficiency. However, when more than one family member is diagnosed with CVID, researchers believe it is the result of autosomal recessive inheritance. Rheumatoid arthritis, vitiligo (autoimmune disorder that causes white patches on the skin), hemolytic anemia (type of anemia that occurs when blood cells are destroyed prematurely), thrombocytopenia (low levels of platelets) and neutropenia (low levels white blood cells called neutrophils) have all been associated with CVID.
Initially, the disorder was called acquired agammaglobulinemia. This name generally applied to patients who developed the immunodeficiency when they were 20-50 years old. However, today the use of the term is discouraged in order to avoid confusion with the acquired immune deficiency syndrome (AIDS). Instead, CVID that develops later in life is now referred to as adult-onset hypogammaglobulinemia.
Prognosis depends on the extent of damage to the lungs and other organs, as well as how successfully infections are prevented. In general, the expected survival rate for male and female patients is 92% and 94%, respectively. Factors associated with fatality include low levels of IgG, poor T-cell responses to antigens and a low percentage of B cells. Fatalities related to CVID are usually the result of lymphoma (cancer of the lymph nodes). Other potential causes of death include cor pulmonale (right-sided heart failure) secondary to chronic pulmonary infection, liver failure (caused by viral or autoimmune hepatitis) and malnutrition (resulting from gastrointestinal tract disease).
While there is currently no cure for CVID, treatment can help alleviate symptoms and prevent infections that are associated with the disease. Since the cause of CVID is poorly understood, there is currently no known method of prevention.
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