As a prominent example, anti-Cytotoxic T-Lymphocyte-Associated Protein 4 (CTLA-4) antibodies, the first approved checkpoint-blockade therapy for cancer, were shown to exert their beneficial effects in cancer by decreasing Treg cells in mouse models [10], though the relevance of this mechanism in patients is still under debate [11,12]. The gene discussed is CTLA4; the disease is cancer.