,20,32,40 Mutations in BCOR and its homolog, BCORL1, were first described in adult AML presenting in 5% to 10% of patients (mostly detected in secondary- and therapy-related AML) associated with inferior outcome.41, 42, 43 In children with AML, BCOR/BCORL1 mutations were present in only 2.9% to 3.4% of patients.13 The gene discussed is BCOR; the disease is acute myeloid leukemia.