Cytogenetic analysis coupled with gene expression profiling has been used to classify T-ALL into several subgroups: TAL1/LMO1/2-, TLX1/3-, HOXA/MEISI-, LMO2/LYL1, and NKX2-1-positive T-ALL cases (25–27). The gene discussed is LYL1; the disease is acute lymphoblastic leukemia.