H22 is different from IgG for Fc receptor binding in terms of binding epitope and Fc gamma receptor I (CD64) specificity rather than other type of Fc receptors (CD32, CD16)22, and this has been applied for the development of immunotoxins targeting CD64-positive human myeloid leukemia in previous studies19, 23, 39, 40. The gene discussed is FCGR1A; the disease is myeloid leukemia.