JAK2 and chronic myelogenous leukemia, BCR-ABL1 positive: In pre-B and T-lymphoid forms ETV6 is respectively fused with JAK2 exons 17 and 19, both retaining the JH1 tyrosine kinase domain, while in the single atypical CML case reported the breakpoint lay farther upstream to include the JH2 pseudokinase domain [27], [28].