This expansion was mostly accounted for by PTPN11-mutated JMML, which also showed a larger percentage of myeloid progenitors compared with healthy BM within the CD34+CD38+ compartment (Supplementary Fig. S1C), consistent with the major granulo-monocytic expansion observed in patients with this subtype of JMML. The gene discussed is PTPN11; the disease is juvenile myelomonocytic leukemia.