Onychomadesis in a Patient with Immunoglobulin Class Switch Recombination Deficiency

Immunoglobulin class switch recombination deficiencies (ig csr deficiencies) or hyperigm syndromes (higm) are a group of primary immunodeficiency diseases, characterized bydefective cd40 signaling of b cells, resulting in reduced csr and somatic hypermutation.the affected patients are characterized by low serum levels of igg and iga, and normal orelevated levels of igm, which lead to an increased susceptibility to infections.we describe a 3 year-old boy with frequent bacterial infections of the skin and respiratorytract, mucosal ulcers, and diarrhea. he experienced onychomadesis of both fingernails andtoenails during a recent bacterial infection. quantitative immunoglobulin measurementsrevealed high levels of serum igm and very low levels of igg, iga, and ige. clinical andimmunologic studies supported the diagnosis of higm.exclusion of cd40l, cd40, aid and ung genes by molecular analysis in this patientmay suggest a new form of selective csr deficiency.