FCAR (Fc alpha receptor) is a transmembrane immune receptor located on chromosome 19.4 within the leukocyte receptor cluster that binds to the Fc region of IgA immunoglobulins and mediates immune responses including cytokine production 1. The receptor functions as an immune receptor with transmembrane signaling capability, localizing to the plasma membrane and specific granule membranes of immune cells 2. FCAR has emerged as a significant biomarker and therapeutic target in multiple disease contexts. In sepsis, FCAR was identified as an independent predictor of poor survival in patients and is associated with neutrophil extracellular trap (NET) expression and organ injury 3. Similarly, in acute liver failure, FCAR was identified among key NET-related genes in disease pathogenesis 4. FCAR variants (rs4806606-G and rs8112766-G) show protective associations with chr19 obstructive pulmonary disease susceptibility in Chinese populations and interact with environmental exposures 5. In IgA nephropathy, a progressive kidney disease, FCAR was identified as a novel genome-wide significant risk locus, with convergence on inflammatory signaling pathways 6. Additionally, FCAR was identified as a potential drug target for migraine treatment showing minimal side effects and interaction with current migraine medications 7. In acute myeloid leukemia, FCAR+ macrophages were significantly elevated in chemotherapy-resistant patients and associated with immune metabolic regulation 2.