The classification of T-ALL/LBL, broadly used in the literature, is complex and based on the oncogenic activation of several transcription factors (TF), driving leukaemia development and defining major genetic subtypes: TAL1, TAL2, TLX1, TLX3, HOXA, LMO1/2, LMO2/LYL1, NKX2-1, SPI1 [34, 35]. The gene discussed is TLX3; the disease is acute lymphoblastic leukemia.