A subset of human AML cases show deletions on chromosome 9q, which are specifically associated with the t(8;21) translocation yielding AML1-ETO. The effects of del(9q) result from the loss of two genes, transducin-like enhancer of split 1 (TLE1) and TLE4, in the Notch signaling pathway. The gene discussed is TLE1; the disease is acute myeloid leukemia.