Acute myelogenous leukaemia M4-like were notable for the presence of two distinct populations of leukaemia with differing densities of CD45 and side scatter, distinct from each other and from normal leukocytes, with one subpopulation bearing immature markers (CD34 and CD117), and the other monocyte markers CD14 and/or CD64. The gene discussed is FCGR1A; the disease is acute myeloid leukemia.