Indeed, all 5 out of 5 cancer patients who received anti–CTLA-4 treatment with or without combination with anti–PD-1 and 3 out of 3 humanized mice injected with anti–CTLA-4 displayed a specific accumulation of autoreactive mature naive B cells, thereby demonstrating that CTLA-4 blockade results in autoreactive B cell production. The gene discussed is CTLA4; the disease is cancer.