Selective deficiency of immunoglobulin A (IGAD) is the most common form of primary immunodeficiency, with an incidence of approximately 1 in 600 individuals in the western world (Cunningham-Rundles, 2001). The umbrella term 'common variable immunodeficiency' (CVID; see 607594) ... Selective deficiency of immunoglobulin A (IGAD) is the most common form of primary immunodeficiency, with an incidence of approximately 1 in 600 individuals in the western world (Cunningham-Rundles, 2001). The umbrella term 'common variable immunodeficiency' (CVID; see 607594) refers to a group of disorders characterized by a deficiency in all Ig isotypes. Individuals with symptomatic IGAD and individuals with CVID suffer from recurrent sinopulmonary and gastrointestinal infections and have an increased incidence of autoimmune disorders and of lymphoid and nonlymphoid malignancies. IGAD and CVID can coexist in families, and some individuals initially present with IGAD and then develop CVID. These observations suggested that some cases of IGAD and CVID may have a common etiology (Castigli et al., 2005).
By studying cohorts of immunodeficient individuals from Europe (162 individuals with CVID) and the US (19 individuals with CVID and 16 with IGAD), Salzer et al. (2005) and Castigli et al. (2005) found that mutations in the TNFRSF13B ... By studying cohorts of immunodeficient individuals from Europe (162 individuals with CVID) and the US (19 individuals with CVID and 16 with IGAD), Salzer et al. (2005) and Castigli et al. (2005) found that mutations in the TNFRSF13B gene (604907), encoding transmembrane activator and CAML interactor (TACI), were associated with both familial and sporadic forms of the disease. Martin and Dixit (2005) noted that 3 of the 6 mutations were found in both cohorts and were seen in both familial and sporadic cases, suggesting that a small number of common mutations could account for most TACI-associated immunodeficiency cases.