Whilst the breakpoints in some TKs are tightly clustered, such as the PDGFRA exon 12 breakpoint region [16, 17], others can be spread over large distances, such as the ABL1 breakpoint region in CML, which spans around 140 Mb [18]. The gene discussed is PDGFRA; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.