ABSTRACT:Common variable immunodeficiency is the most prevalent clinically significant antibody deficiency at all ages. The disorder is defined principally by characteristic infection susceptibility with hypogammaglobulinemia and impaired-specific antibody response. Several recent large registry-based studies have defined distinct phenotypic subtypes. Several studies have also correlated specific immunologic markers with these phenotypes. The biochemical or genetic abnormality in the majority of patients remains unknown. Recently, several molecular genetic lesions have been defined. Among these, mutations of inducible costimulator, and CD19, appear to be disease causing by themselves. These account for about 1% of cases. Other mutations or polymorphisms, such as in the human homolog of Escherichia coli MutS 5 (MSH5), and transmembrane activator and calcium mobilizing ligand interactor, seem to be disease associated in 5-10% of patients, but may require additional immunologic abnormalities for full expression of the phenotype, as unaffected heterozygotes have also been described.
Clinical Features of CVIDCommon variable immunodeficiency (CVID) is a form of predominantly humoral primary immunodeficiency. Symptoms may begin at any time of life, including the extremes of both young and old age (1-3). Major characteristics include recurrent infections, principally bacterial and viral of the respiratory tract. In one recent French registry study (DEFI Study) of 252 patients, 95% had one or more of the following: bronchitis, sinusitis, and pneumonia. Not surprisingly, common bacterial pathogens such as Streptococcus pneumoniae and Hemophilus influenzae were most often isolated. Granulomatous or lymphocytic interstitial lung disease occurs in a subset of patients and may be associated with human herpesvirus 8 (4). Granulomas may also involve other organs and resemble sarcoid. Furthermore, in the DEFI study, 47% of patients had diarrhea (intermittent or chronic); Giardia, Salmonella, and Campylobacter were common isolates (2). Enteroviral intestinal infections may disseminate and cause meningoencephalitis.Autoimmune disease is common in CVID (5). One recent survey reviewed seven published studies comprising 831 patients altogether (6). The reported prevalences of autoimmune disease ranged from 17 to 50%, and it was present in 27% of the overall patient population. Immune thrombocytopenic purpura and autoimmune hemolytic anemia were by far the most common diagnoses, followed by aseptic nonerosive seronegative inflammatory arthritis. Additional disorders observed include inflammatory bowel disease, vasculitides (some resembling systemic lupus erythematosus), and others. 1 Approximately 10% of patients with CVID have a lymphoproliferative disorder (7). This manifests most frequently as splenomegaly, lymphadenopathy and interstitial lung disease, as described above. The relative risk of lymphoma in patients with CVID compared with the general population is in the range of 10-to 20-fold higher (7). Most of these are B-cell n...