Because gain-of-function mutations in isocitrate dehydrogenase 1 (IDH1) can be key drivers of malignancies of the T cell lineage, they analyzed the T cell compartment in a conditional knock-in (KI) mouse model of mutant IDH1 and observed the development of a spontaneous T cell acute lymphoblastic leukemia (T-ALL) in these animals. This evidence concerns the gene IDH1 and T-cell acute lymphoblastic leukemia.