For the analysis of miRNA references within these samples, we have chosen samples that were detected > 25% viable according to FSC/SSC criteria and presenting with > 60% human CD19-positive cells (Fig. 1), thereby identifying 22 spleen-, 22 BM-, and 12 CNS-derived leukemia samples which is concordant with previous findings on varying CNS engraftment phenotypes17. The gene discussed is CD19; the disease is leukemia.