Of note, in 2/5 cases Ph-negative phenotype became evident after TKI, with BCR::ABL1 decrease and JAK2 increase (15, 22); in addition, in one of these two cases, BM performed at the time of initial CML diagnosis retrospectively revised showed not only MKs with hypo-lobate nuclei, typical of CML, but even large and occasionally clustering MKs with bulbous nuclei (22). This evidence concerns the gene JAK2 and chronic myelogenous leukemia, BCR-ABL1 positive.