Hsu et al. now used an improved variant of the UCT, where in parallel CD34+ cells from a haploidentical donor were transplanted.1 Supportive co-transplantation of purified peripheral blood CD34+ cells (CD34 is a marker for hematopoietic stem cells) from an HLA-haploidentical donor leads to an early recovery of neutrophils and thus closes the gap between pretransplant conditioning (eradicating residual leukemic cells and suppressing host immunity to prevent rejection) and engrafting of the UCT cells which reduces the risk for infectious complications caused by protracted neutropenia. The gene discussed is CD34; the disease is neutropenia.