Common Variable Immunodeficiency
Common Variable Immunodeficiency
The diagnosis 'common variable immunodeficiency' (CVID) describes patients presenting with hypogammaglobulinemia of unknown origin and variable immunological and clinical phenotypes. The most common symptoms are severe, recurrent and sometimes chronic bacterial infections mainly of the respiratory and gastrointestinal tracts.
Based on the 1999 criteria issued by the American and European societies for immunodeficiency, the diagnosis of CVID can be made if the following criteria are fulfilled: a male or female patient who exhibits a marked decrease of IgG (at least two standard deviations below the mean for age) and of at least one of the IgM or IgA isotypes; onset of immunodeficiency at greater than 2 years of age; absence of isohemagglutinins and/or poor response to vaccines; and other defined causes of hypogammaglobulinemia have been excluded. Most important is the exclusion of other primary immunodeficiencies and secondary causes of hypogammaglobulinemia (Table 1).
It is important to note that only a small percentage of patients taking any of the drugs mentioned in Table 1 will develop a secondary hypogammaglobulinemia, suggesting an individual predisposition. While some of the drug reactions are due to toxic effects, others may be induced by an allergic reaction.
The listed infections usually do not cause hypogammaglobulinemia; therefore, an underlying predisposition is also likely in these patients. Only mutations in SH2D1A (encoding SAP) causing X-chromosomal lymphoproliferative syndrome are confirmed to be associated with Epstein Barr virus-driven hypogammaglobulinemia.
Definition of Common Variable Immunodeficiency
The diagnosis 'common variable immunodeficiency' (CVID) describes patients presenting with hypogammaglobulinemia of unknown origin and variable immunological and clinical phenotypes. The most common symptoms are severe, recurrent and sometimes chronic bacterial infections mainly of the respiratory and gastrointestinal tracts.
Based on the 1999 criteria issued by the American and European societies for immunodeficiency, the diagnosis of CVID can be made if the following criteria are fulfilled: a male or female patient who exhibits a marked decrease of IgG (at least two standard deviations below the mean for age) and of at least one of the IgM or IgA isotypes; onset of immunodeficiency at greater than 2 years of age; absence of isohemagglutinins and/or poor response to vaccines; and other defined causes of hypogammaglobulinemia have been excluded. Most important is the exclusion of other primary immunodeficiencies and secondary causes of hypogammaglobulinemia (Table 1).
It is important to note that only a small percentage of patients taking any of the drugs mentioned in Table 1 will develop a secondary hypogammaglobulinemia, suggesting an individual predisposition. While some of the drug reactions are due to toxic effects, others may be induced by an allergic reaction.
The listed infections usually do not cause hypogammaglobulinemia; therefore, an underlying predisposition is also likely in these patients. Only mutations in SH2D1A (encoding SAP) causing X-chromosomal lymphoproliferative syndrome are confirmed to be associated with Epstein Barr virus-driven hypogammaglobulinemia.
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