A novel activation-induced cytidine deaminase mutation in an adult with hyper-immunoglobulin M syndrome

Abstract

The hyper-immunoglobulin M (HIGM) syndromes are a group of immunodeficiencies that exhibit low or absent levels of immunoglobulin G (IgG), IgA, and IgE and normal to high levels of IgM.1 These syndromes are characterized by inherited defects in genes encoding for the CD40L or CD40 molecule, or defects in class-switch recombination (CSR) in B cells.2 Activation-induced cytidine deaminase (AID) is a protein that is required for CSR in B cell differentiation.3,4 A mutation in the activation-induced cytidine deaminase (AICDA) gene that encodes AID causes the autosomal recessive (AR) form of HIGM syndrome known as HIGM2.