background: defects in b cell class switch recombination (csr) are a heterogeneous and yet very uncommon group of disorders which all have a genetic basis uniformly leading to hyper igm (higm) syndrome. due to the rare frequency of these conditions, a very small number of case series have been conducted on the affected patients. objective: to shed some light on the morbidity and mortality regar...

immunoglobulin class switch recombination deficiencies (ig csr deficiencies) or hyper igm syndromes (higm) are a group of primary immunodeficiency diseases, characterized by defective cd40 signaling of b cells resulting into a csr and a somatic hypermutation. the affected patients are characterized with reduced serum levels of igg and iga, and normal or elevated level of igm, which lead to incr...

Several genetic defects in class switch recombination, which lead to a hyper-IgM syndrome, have been described recently in humans. In addition to the well known role of CD40-ligand-CD40 interaction, these pathologies demonstrate definitively the requirement of CD40-mediated nuclear factor kappa B activation and the essential role of a recently described molecule, the activation-induced cytidine...

Background: Defects in B cell class switch recombination (CSR) are a heterogeneous and yet very uncommon group of disorders which all have a genetic basis uniformly leading to hyper IgM (HIgM) syndrome. Due to the rare frequency of these conditions, a very small number of case series have been conducted on the affected patients. Objective: To shed some light on the morbidity and mortality regar...

Recent work indicates that mutations in a cytidine deaminase homologue ablate both immunoglobulin class switch recombination and somatic hypermutation. These findings now explain cases of autosomal hyper-IgM syndrome and reveal that critical components for key functions of B cells require RNA editing.

The activation-induced cytidine deaminase (AID) gene, specifically expressed in germinal center B cells in mice, is a member of the cytidine deaminase family. We herein report mutations in the human counterpart of AID in patients with the autosomal recessive form of hyper-IgM syndrome (HIGM2). Three major abnormalities characterize AID deficiency: (1) the absence of immunoglobulin class switch ...

The Journal of Clinical Investigation | July 2003 | Volume 112 | Number 1 RNase. Proc. Natl. Acad. Sci. U. S. A. 100:4102-4107. 14. Shinkura, R., et al. 2003. The influence of transcriptional orientation on endogenous switch region function. Nat. Immunol. 4:435–441. 15. Yu, K., Chedin, F., Hsieh, C.L., Wilson, T.E., and Lieber, M.R. 2003. R-loops at immunoglobulin class switch regions in the ch...

Thirteen Japanese patients with hyper-IgM syndrome but normal CD40 ligand were characterized. All patients had mutations in AID (activation-induced cytidine deaminase) gene. Five of them had a missense mutation of Arg112His. In all patients, serum IgG, IgA and IgE levels were undetectable, B cells failed to produce detectable amounts of IgE even if cultured them with anti-CD40 and IL-4. Somatic...