Differentiation therapy has been approved as being effective for hematopoietic malignancies, such as all-trans-retinoic acid and arsenic trioxide for acute promyelocytic leukemia.32–34 Given the critical role of UTX in the regulation of HSPCs, we hypothesized that releasing the differentiation block due to UTX deficiencies could benefit patients with UTX mutations. This evidence concerns the gene KDM6A and acute promyelocytic leukemia.