Instead, they described the enrichment of LSCs in the CD34+/CD7+ fraction.11 In addition, Chiu et al. showed that a subset of cells that are CD7+CD1a− from primary T-ALL patient samples are enriched for LSC by xenograft studies in immune-deficient mice and noted CD34 as a reliable stemness marker for some but not all of the samples tested.62 Advanced single-cell sequencing technologies have also revealed significant heterogeneity within the LSC population in T-ALL. The gene discussed is CD7; the disease is acute lymphoblastic leukemia.