From Dysgammaglobulinemia to Autosomal-Dominant Activation-Induced Cytidine Deaminase Deficiency: Unraveling an Inherited Immunodeficiency after 50 Years.

The genetic investigation of a family presenting with a dominant form of hyper IgM syndrome published in 1963 and 1975 revealed a R190X nonsense mutation in activation-induced cytidine deaminase. This report illustrates the progress made over 6 decades in the characterization of primary immunodeficiencies, from immunochemistry to whole-exome sequencing.

First report of the Hyper-IgM syndrome Registry of the Latin American Society for Immunodeficiencies: novel mutations, unique infections, and outcomes.

Hyper-IgM (HIGM) syndrome is a heterogeneous group of disorders characterized by normal or elevated serum IgM levels associated with absent or decreased IgG, IgA and IgE. Here we summarize data from the HIGM syndrome Registry of the Latin American Society for Immunodeficiencies (LASID). Of the 58 patients from 51 families reported to the registry with the clinical phenotype of HIGM syndrome, molecular defects were identified in 37 patients thus far. We retrospectively analyzed the clinical, immunological and molecular data from these 37 patients. CD40 ligand (CD40L) deficiency was found in 35 patients from 25 families and activation-induced cytidine deaminase (AID) deficiency in 2 unrelated patients. Five previously unreported mutations were identified in the CD40L gene (CD40LG). Respiratory tract infections, mainly pneumonia, were the most frequent clinical manifestation. Previously undescribed fungal and opportunistic infections were observed in CD40L-deficient patients but not in the two patients with AID deficiency. These include the first cases of pneumonia caused by Mycoplasma pneumoniae, Serratia marcescens or Aspergillus sp. and diarrhea caused by Microsporidium sp. or Isospora belli. Except for four CD40L-deficient patients who died from complications of presumptive central nervous system infections or sepsis, all patients reported in this study are alive. Four CD40L-deficient patients underwent successful bone marrow transplantation. This report characterizes the clinical and genetic spectrum of HIGM syndrome in Latin America and expands the understanding of the genotype and phenotype of this syndrome in tropical areas.

A novel form of non-X-linked hyperigm associated with growth and pubertal disturbances and with lymphoma development.

HyperIgM syndrome is a heterogenous immunodeficiency characterized by impaired class-switch recombination due to different molecular abnormalities. We report on two female patients affected by a novel syndrome associating HIGM, growth and pubertal disturbances, and severe lymphoid hyperplasia with eventual development into lymphomas, suggesting a DNA repair defect.