BCR and chronic myelogenous leukemia, BCR-ABL1 positive: Among BCR::ABL1 variants, micro BCR::ABL1 (μ-bcr) is the fusion of BCR exon 19 and ABL1 exon 2 (e19a2), which results in a 230-kDa protein, and can be a molecular diagnostic marker for neutrophilic-chronic myeloid leukemia (CML-N) [3].