Patients with B-other ALL have poorer outcomes than ALL with either ETV6-RUNX1 and Hyperdiploid > 50, which together constitute the majority of MR patients.39,40 High WCC (>50) is a well-established marker for poor patient outcome in the clinic,41,42 indicative of a more aggressive disease which is likely accountable for the observed strong engraftment of these samples. The gene discussed is RUNX1; the disease is acute lymphoblastic leukemia.