Description of a Novel Pathogenic Variant in the ARPC1B and a Severe Allergy in Two Infants.

Actinrelated protein 2/3 complex subunit 1B (ARPC1B) deficiency is an inborn error of immunity (IEI) characterized by a combination of immunodeficiency and immune dysregulation and classified as an IEI with allergic manifestations. Here, we describe two patients with pathogenic variants in the ARPC1B gene. The first patient presented with eczema and bronchospasm at six months of age. The second patient presented with eczema and milk protein allergy at five months of age. The c.899_944 (p.Glu300Glyfs*7) pathogenic variant was previously described, whereas the c.863del (p.Pro288Leufs*9) variant was novel. ARPC1B deficiency should be considered because of the severe allergic manifestations at an early age.