PMC4696471_01
A, B: Increased blasts and platelets in BM examination of initial diagnosis. C, D: Chromosomal aberrations revealed in cytogenetic analysis. E: FISH indicated the rearrangement between ABL and BCR genes. F: Bi-directional sequencing for confirmation of CALR 52-bp mutation.
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BM aspirate smears showed hypercellular marrow with increased blasts (Figure 1A) and platelets (Figure 1B). Cytogenetic analysis indicated the presence of der(11), der(17) and der(18) chromosome abnormalities in different clonal populations harboring 46XX karyotype with t(9;22) (q34;q11) (Figure 1C, 1D) in addition to the observed BCR-ABL fusion gene in BM metaphases by fluorescence in situ hybridization (FISH) (Figure 1E). Combining the previously published studies with current data, including a high platelet count and the absence of JAK2V617F mutation, we were encouraged to study mutations in exon 9 of CALR by bidirectional sequencing in the following investigations (Figure 1F), which surprisingly revealed a del52CALR mutant with a high allele burden in granulocyte population.