Primary B Cell Immunodeficiencies: Comparisons and Contrasts

Sophisticated genetic tools have made possible the identification of the genes responsible for most well-described immunodeficiencies in the past 15 years. Mutations in Btk, components of the pre-B cell and B cell receptor (λ5, Igα, Igβ), or the scaffold protein BLNK account for approximately 90% of patients with defects in early B cell development. Hyper-IgM syndromes result from mutations in CD40 ligand, CD40, AID, or UNG in 70–80% of affected patients. Rare defects in ICOS or CD19 can re...