BACKGROUND Common variable immunodeficiency (CVID) is characterized by late-onset hypogammaglobulinemia in the absence of predisposing factors. The genetic cause is unknown in the majority of cases, and less than 10% of patients have a family history of the disease. Most patients have normal numbers of B cells but lack plasma cells. METHODS We used whole-exome sequencing and array-based comparative genomic hybridization to evaluate a subset of patients with CVID and low B-cell numbers. Mutant proteins were analyzed for DNA binding with the use of an electrophoretic mobility-shift assay (EMSA) and confocal microscopy. Flow cytometry was used to analyze peripheral-blood lymphocytes and bone marrow aspirates. RESULTS Six different heterozygous mutations in IKZF1, the gene encoding the transcription factor IKAROS, were identified in 29 persons from six families. In two families, the mutation was a de novo event in the proband. All the mutations, four amino acid substitutions, an intragenic deletion, and a 4.7-Mb multigene deletion involved the DNA-binding domain of IKAROS. The proteins bearing missense mutations failed to bind target DNA sequences on EMSA and confocal microscopy; however, they did not inhibit the binding of wild-type IKAROS. Studies in family members showed progressive loss of B cells and serum immunoglobulins. Bone marrow aspirates in two patients had markedly decreased early B-cell precursors, but plasma cells were present. Acute lymphoblastic leukemia developed in 2 of the 29 patients. CONCLUSIONS Heterozygous mutations in the transcription factor IKAROS caused an autosomal dominant form of CVID that is associated with a striking decrease in B-cell numbers. (Funded by the National Institutes of Health and others.)

No abstract

The clinical and immunologic features of two adolescent boys who had recurrent pyogenic infections are judged to constitute a new syndrome. Its characteristics include: recurrent cutaneous, pulmonary, and joint abscesses; growth retardation; coarse facies; chronic dermatitis; exquisite immediate hypersensitivity associated with exceptionally high serum concentrations of IgE and eosinophilia; and depressed in vivo cellular immunity and antibody formation. These patients lacked evidence of respiratory allergy or parasitism. Atopic dermatitis was not present in one boy and the physical characteristics of the other boy's dermatitis were not typical for that entity. Concentrations of immumnoglobulins G, A, M, D and the various IgG subtypes were normal, as were natural antibody titers to red cell antigens. Nevertheless, depressed anamnestic antibody responses were noted to diphtheria and tetanus antigens and neither patient demonstrated responses to primary immunization with KLH, typhoid, and DNCB antigens. Complement and polymorphonuclear functions were normal. In vitro lymphocyte studies done demonstrated normal DNA synthesis in phytohemagglutinin and staphylococcal antigen-stimulated cultures and MIF production by some antigen-stimulated cultures from each. The explanation for the undue susceptibility to infection, increased IgE production, subnormal antibody formation, and impaired in vivo cell-mediated immunity in these patients remains conjectural.

Fungi were isolated from a house associated with four leukemic patients from three families because of the possibility that mycotoxin-producing strains might be present. Extracts of several of the isolated fungal species produced toxic effects in one or more species of animals. Aflatoxin-producing Aspergillus parasiticus was isolated from non-leukemia-associated houses with the exception of Trichoderma, Verticillium, and Monotospora. We believe that certain mycotoxins may be related to pathogenesis of leukemia, possibly as an expression of their immunosuppressive effects.