T cell acute lymphoblastic leukemia (T-ALL) is a cancer of early thymocytes and is characterized by recurrent chromosomal rearrangements that activate oncogenic transcription factors such as TAL1/2, LMO1/2/3, NKX2.1/2.2, TLX1, TLX3, or HOXA. The gene discussed is LMO1; the disease is T-cell acute lymphoblastic leukemia.