MAJOR CATEGORIES OF ANTIBODY DEFICIENCY
ANTIBODY DEFICIENCY ASSOCIATED WITH ABSENT B CELLS
B-cell maturation beyond the pre-B-cell stage found in bone marrow, requires signals received through the pre-B-cell receptor complex. The pre-B-cell receptor is composed of the μ chains, surrogate light chains (heterodimers of λ constant region with V pre-β), and the signal-transducing components Igα and Igβ. The activities of the protein BTK (Bruton’s tyrosine kinase) and BLNK (B-cell linker protein) are also essential for the transduction of signals received via the B-cell (and pre-B-cell) receptors. Therefore, it is not surprising that mutations in each of these elements causes early-onset antibody deficiency associated with lack of circulating B cells.