MS4A6A (membrane spanning 4-domains A6A) is a tetraspan transmembrane protein involved in immune cell signaling and inflammatory responses. As a component of multimeric receptor complexes 1, MS4A6A functions in signal transduction at the plasma membrane and trans-Golgi network, demonstrating protein binding capacity consistent with its role in receptor assembly [GO Annotations]. The gene is predominantly expressed in immune cells, particularly microglia, macrophages, and endothelial cells 234. MS4A6A regulates inflammatory signaling through the IKK/NF-κB pathway 5, controlling endothelial dysfunction and monocyte adhesion. In Alzheimer's disease, MS4A6A expression in microglia promotes amyloid-beta clearance and neuroprotective responses; MS4A6d deficiency impairs microglial phagocytosis of amyloid plaques and exacerbates neuroinflammation 4. The protective MS4A6A variant rs610932 is associated with reduced Alzheimer's disease risk 6. In lung cancer and lupus nephritis, MS4A6A serves as a driver gene linked to immune cell infiltration and disease severity 78. Additionally, MS4A6A compensates functionally for FcεRIβ in human mast cells, supporting IgE-mediated allergic responses 1, suggesting its role in allergy susceptibility.