Activated PI3K-delta syndrome

Definition

A rare, genetic, primary immunodeficiency disease characterized by increased susceptibility to recurrent and/or severe bacterial and viral infections (in particular, sinopulmonary bacterial and herpesvirus infections), chronic benign lymphoproliferation (manifesting as lymphadenopathy, hepatosplenomegaly and focal nodular lymphoid hyperplasia), and/or autoimmune disease (including immune cytopenias, juvenile arthritis, glomerulonephritis and sclerosing cholangitis). Immunophenotypically, variable degrees of agammaglobulinemia with increased IgM levels, increased circulating transitional B cells, decreased naïve CD4 and CD8 T-cells with increased CD8 effector/memory T cells are observed.