AICDA and hyper-IgM syndrome type 2: 26 Revy Revy P P Muto Muto T T Levy Levy Y Y Geissmann Geissmann F F Plebani Plebani A A Sanal Sanal O O Activation-induced cytidinedeaminase (AID) deficiency causes the autosomal recessive form of the Hyper-IgM syndrome (HIGM2) Activation-induced cytidinedeaminase (AID) deficiency causes the autosomal recessive form of the Hyper-IgM syndrome (HIGM2) Cell.