Combining the results of the present study with our previous finding, we found that rs11571315 and rs16840252 of CTLA4 were associated with the adverse reaction of post-haematopoietic stem cell transplantation in patients with acute lymphocytic leukemia (27) and immune thrombocytopenia (28). This evidence concerns the gene CTLA4 and autoimmune thrombocytopenic purpura.