ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Most of them are focused on the presence and location of the BCR/ABL1 fusion in CML patients with masked Ph chromosome and commonly achieved by application of commercial FISH probes, which have been proved to be very useful to identify the presence and location of the BCR/ABL1 fusion gene in CML patients with no distinguishable Ph chromosome.