FCER1G (Fc epsilon receptor Ig) functions as a critical adapter protein containing an immunoreceptor tyrosine-based activation motif (ITAM) that transduces activation signals from various immunoreceptors. As a component of the high-affinity IgE receptor complex, FCER1G mediates allergic inflammatory signaling in mast cells and selectively mediates IL-4 production by basophils 1. The protein associates with pattern recognition receptors CLEC4D and CLEC4E to form functional signaling complexes in myeloid cells, where binding of mycobacterial trehalose 6,6'-dimycolate triggers ITAM phosphorylation, activating SYK, CARD9, and NF-κB pathways that drive antigen-presenting cell maturation 1. FCER1G is highly expressed in immune cells, particularly monocytes/macrophages and dendritic cells, and plays important roles in cancer immunity as part of innate-like T cells with high cytotoxic potential 21. The gene shows significant upregulation across multiple disease contexts including acute myocardial infarction, liver fibrosis, and various cancers, where it correlates with immune cell infiltration and inflammatory responses 341. Clinical studies suggest FCER1G expression may serve as a diagnostic biomarker and potential therapeutic target in immune-mediated diseases and cancer immunotherapy 1.