A combined immunodeficiency with severe infections, inflammation, and allergy caused by ARPC1B deficiency

Recently, a novel syndrome of combined immunodeficiency, allergy, and “auto”inflammation caused by mutations in the ARPC1B gene has been reported. Analysis of patient-derived hematopoietic cells has shown a defect in actin polymerization, which resulted in a wide range of clinical manifestations and immunologic-hematologic features. We report on the immunologic, cellular, and molecular phenotypes in 14 patients with biallelic ARPC1B mutations and variable clinical presentations (Fig 1, A and B; see Fig E1, A, and Table E1 in this article's Online Repository at www.jacionline.org; for case descriptions, see this article's Online Repository at www.jacionline.org), helping to delineate the broad spectrum of this novel disease and presenting unreported insights into cell-intrinsic defects involving regulatory T (Treg) cells and natural killer (NK) cells, potential players in the immune dysregulation and susceptibility to viral infections observed in these patients.