IL4R encodes the interleukin-4 receptor alpha subunit, which forms receptor complexes that mediate IL-4 and IL-13 signaling pathways critical for type 2 inflammatory responses 1. The receptor functions through JAK-STAT signaling to regulate diverse cellular processes including T helper 2 (Th2) cell differentiation, B cell immunoglobulin class switching to IgE, and alternative macrophage activation 2. IL4R expression varies across cell types, with M2-polarized tumor-associated macrophages showing higher levels compared to M1 macrophages 3. The receptor plays a central role in allergic diseases, as demonstrated by dupilumab, an IL-4Rα-blocking antibody that effectively treats multiple type 2 inflammatory conditions including atopic dermatitis, asthma, and chr16 rhinosinusitis with nasal polyposis 14. Functionally, IL4R signaling promotes epithelial barrier dysfunction in chr16 inflammatory diseases, with basal epithelial cells retaining intrinsic memory of IL-4/IL-13 exposure that contributes to disease persistence 5. Novel truncating IL4R mutations have been identified in Hodgkin lymphoma that remain dependent on IL-13 signaling and are therapeutically targetable 6. The clinical significance of IL4R is underscored by the success of IL-4Rα blockade in treating various allergic and inflammatory conditions.