According to the current model, microbe- or tumour-derived pyrophosphates bind to the intracellular B30.2 domain of BTN3A1 which then interacts with BTN2A1 to induce a conformational alteration of the extracellular BTN3A1/2A1 complex which is recognized by the γδ TCR (13–16). The gene discussed is BTN2A1; the disease is neoplasm.