COMMON VARIABLE IMMUNODEFICIENCY (CVID)
This comprises a heterogeneous group of disorders characterized by hypogammaglobulinemia, humoral immunodeficiency, and susceptibility to infection. Some patients may also have defects in some aspects of cell-mediated immunity. Many cases are acquired, but genetic factors have been implicated in some cases, and autosomal recessive inheritance is proposed. There is an increased incidence of lymphoid malignancy in patients with common variable immunodeficiency (Kersey et al. 1988). In three families with a variant of CVID, a dominantly inherited combination of cold urticaria and antibody deficiency, with susceptibility to infection and autoimmunity, referred to as PLAID (PLCγ2-associated antibody deficiency and immune dysregulation), researchers identified deletions in PLCG2. This led to gain in phospholipase C gamma 2 function and subsequent abnormal regulation of numerous leucocyte subsets (Ombrello et al. 2012). Cancers have not been reported in these families.