To study the full spectrum of miRNAs involved in normal and malignant T-cell development, we performed small RNA-sequencing on 48 primary T-ALL patient samples of different T-ALL subgroups (13 immature, 14 TLX1+ or TLX3+, 15 TAL-rearranged and 6 HOXA-overexpressing T-ALL samples), CD34+ and CD4+CD8+ normal thymocyte subsets from healthy donors and a panel of 7 T-ALL cell lines (Fig. 1a). The gene discussed is CD34; the disease is acute lymphoblastic leukemia.