The detection of high‐risk ACAs comprising monosomy 7 and deletion of chromosome 7q or complex karyotype, recurrent copy number changes such as deletion of chromosome 9p or 7p, and in particular the identification of aberrant RAG‐mediated recombination in the genes IKZF1, CDKN2A/B and RUNX1 in this paediatric cohort corresponded to the data from adult patients with CML.41, 42. The gene discussed is RUNX1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.