The <i>NUP214-ABL1</i> fusion gene is a constitutively active tyrosine kinase that can be detected in 6% of T-cell acute lymphoblastic leukemia (T-ALL) patients, and it can also be found in B-cell acute lymphoblastic leukaemia (B-ALL). The gene discussed is NUP214; the disease is precursor B-cell acute lymphoblastic leukemia.