CTLA4 and autoimmune thrombocytopenic purpura: studied CTLA-4 + 49 A/G in different hematological diseases (AIHA, ITP, and CLL) and found no difference between patients with ITP (N, 60) and healthy participants, but the G allele of CTLA-4 predisposes to AIHA development, particularly among patients with CLL [27].