Agammaglobulinemias

Definition:

There are three major categories of antibody deficiencies: (a) defects in early B cell development, (b) hyper-IgM syndromes (also called class switch recombination defects), and (c) common variable immunodeficiency (CVID). Category (a) consists of agammaglobulinaemias (AGM). Defects in early B cell development are characterized by the onset of recurrent bacterial infections in the first 5 years of life, profound hypogammaglobulinemia, markedly reduced or absent B cells in the peripheral circulation, and (in the bone marrow) a severe block in B cell differentiation before the production of surface immunoglobulin-positive B cells. Mutations in Btk, the gene responsible for X-linked agammaglobulinemia (XLA), account for approximately 85% of affected patients. Approximately half of the remaining patients have mutations in genes encoding components of the pre-B cell receptor (pre-BCR) or BCR, including mu heavy chain (IGHM); the signal transduction molecules Ig-alpha (CD79A) and Ig-beta (CD79B); and lambda 5 (IGLL1), which forms the surrogate light chain with Vpre-B. A small number of patients with defects in BLNK, a scaffold protein that assembles signal transduction molecules activated by cross-linking of the BCR, have been reported.

References:

Biomedical Dictionary

The Biomedical Dictionary is a comprehensive and professional collection of biological academic terms and subject datas. All explanations are supported by authoritative books or high impact factor literatures, and you can acquire accurate explanations of the biomedical terms you want to know.
ABCDEFGHIJKLMNOPQRSTUVWXYZ#