[Common variable immunodeficiency. A clinical approach].

Common variable immunodeficiency (CVID) is an immunodeficiency characterized by an impaired ability to produce antibodies associated to multiple clinical phenotypes. The incidence is around 1/50,000 new borns. The age at diagnosis shows 2 peaks, between 1-5 and 16-20 years old. The failure is localized in partially mature B lymphocytes, affects antibody synthesis and class switch from IgM to IgG. Only in 10% of cases, a mutation has been detected, in the others, the genetic defect is unknown. The clinical manifestations are severe and recurrent infections, autoimmunity, gastrointestinal manifestations, lymphoid hyperplasia and a high risk to develop cancer. The most common clinical presentation consists in recurrent sinus-bronchial infections. Hemolytic anemia and thrombocytopenia are frequent autoimmune disorders. Diagnosis must be suspected in a patient with sinus-bronchial infections associated to the different clinical syndrome above described, also significant reduction of immunoglobulin G, reduction of immunoglobulin A or immunoglobulin M. The differential diagnosis of CVID is largely based on the exclusion of other antibody immune deficiencies. Mutation on TACI, ICOS, CD19, BAFF-R, MSH5 must be ruled out for molecular diagnosis. Immunoglobulin replacement therapy diminishes the risk of developing pulmonary complications.