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A novel activation-induced cytidine deaminase (AID) mutation in Brazilian patients with hyper-IgM type 2 syndrome

Nadine Caratão1, Catarina S Cortesão, Pedro H Reis

  • 1Instituto Gulbenkian de Ciência, Rua da Quinta Grande, n° 6, 2780-156 Oeiras, Portugal. nadine.caratao@gmail.com

Clinical Immunology (Orlando, Fla.)
|June 28, 2013
PubMed

Activation-induced cytidine deaminase (AID) is a DNA editing protein that plays an essential role in three major events of immunoglobulin (Ig) diversification: somatic hypermutation, class switch recombination and Ig gene conversion. Mutations in the AID gene (AICDA) have been found in patients with autosomal recessive Hyper-IgM (HIGM) syndrome type 2. Here, two 9- and 14-year-old Brazilian sisters, from a consanguineous family, were diagnosed with HIGM2 syndrome. Sequencing analysis of the exons from AICDA revealed that both patients are homozygous for a single C to G transversion in the third position of codon 15, which replaces a conserved Phenylalanine with a Leucine. To our knowledge, this is a new AICDA mutation found in HIGM2 patients. Functional studies confirm that the homologous murine mutation leads to a dysfunctional protein with diminished intrinsic cytidine deaminase activity and is unable to rescue CSR when introduced in Aicda(-/-)stimulated murine B cells. We briefly discuss the relevance of AICDA mutations found in patients for the biology of this molecule.

Keywords:
AIDAPOBEC1Activation-induced cytidine deaminaseCSRGCHyper-immunoglobulin MMutationNESNLSPISHMactivation-induced cytidine deaminaseapolipoprotein B mRNA editing catalytic polypeptide 1class switch recombinationgene conversionhAIDhuman AIDnuclear export signalnuclear localization signalpropidium iodidesomatic hypermutationwild typewt

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