Both trephine and bone marrow aspiration were consistent with congenital acute leukaemia (B-cell acute lymphoblastic leukaemia (B-ALL)). Immunophenotyping showed the presence of 66-70% cells at the blast window, which was positive for CD79a, CD19, CD20, CD10, CD38, nTdT and CD58 and cyCD22, the presence of immature B lymphoid cells, which showed maturation arrest suggestive of B-ALL. The gene discussed is MME; the disease is precursor B-cell acute lymphoblastic leukemia.