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

To the Editor: Recently, a novel syndrome of combined immunodeficiency, allergy, and “auto”inflammation caused by mutations in the ARPC1B gene has been reported.1-4 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. An increased rate and/or abnormal severity of respiratory tract infections (including pneumonia, bronchopneumonia, and bronchiolitis), and skin infections (including abscesses, erysipelas, extensive warts [Fig 1, B], and molluscum contagiosum), were observed in 71% and 50% of the patients, respectively, whereas severe, protracted bacterial gastrointestinal infections have been diagnosed in a minority of individuals (see Tables E2 and E4 in this article's Online Repository at www.jacionline.org). [...]our cohort delineates a more detailed and larger spectrum of ARPC1B deficiency phenotypes compared with previous reports.