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FMS-like tyrosine kinase 3 (FLT3) is one of the most closely studied genes in blood diseases. Numerous methods have been adopted for analyses, mainly in acute myeloid leukemia (AML) diagnostic work-up. According to international recommendations, the current gold standard approach allows FLT3 canonical mutations to be investigated, providing the main information for risk assessment and treatment choice. However, the technological improvements of the last decade have permitted "black side" gene exploration, revealing numerous hidden aspects of its role in leukemogenesis. The advent of the next-generation sequencing era emphasizes lights and shadows of FLT3 conventional mutational analysis, highlighting the need for a more comprehensive study of the gene. However, more extensive analysis is opening new, unexplored questions whose impact on clinical outcomes is still unknown. The present work is focused on the main topics regarding FLT3 mutational analysis in AML, debating the strengths and weaknesses of the current gold standard approach. The rights and wrongs of NGS introduction in clinical practice will be discussed, showing that a more extensive knowledge of FLT3 mutational status could lead to reconsidering its role in AML management.

The breakpoint cluster region-abelson 1 p190 fusion transcript is the most frequent variant observed in Philadelphia-positive (Ph+) acute lymphoblastic leukemia (ALL). Qualitative-PCR and real-time quantitative PCR are the currently used methods to monitor minimal residual disease (MRD) in Ph+ ALL patients; for the latter, full standardization and an international quality validation are lacking. Here, we developed a droplet digital PCR (ddPCR) assay for MRD monitoring in p190+ ALL cases. The analytical performance was assessed by the limit-of-detection determination, showing a reliability, sensitivity, and precision of the assay of up to 0.001%. Comparison of results obtained with qualitative PCR and ddPCR in 117 follow-up samples from 16 of 26 Ph+ ALL patients showed discordant results in 27% of cases (32 of 117). Real-time quantitative PCR analysis of 19 ddPCR-positive samples with a low tumor burden failed to provide quantitative results in 63% of cases (12 of 19). These results highlight that in p190+ ALL the ddPCR method has a sufficient analytical performance for very low MRD monitoring and for predicting molecular relapse several months before hematologic relapse. In conclusion, MRD monitoring by ddPCR may better stratify Ph+ ALL patients at risk of disease progression.

We report a third-generation sequencing assay on nanopore technology (MinION) for detecting BCR-ABL1 KD mutations and compare the results to a Sanger sequencing(SS)-based test in 24 Philadelphia-positive (Ph+) leukemia cases. Our data indicates that MinION is markedly superior to SS in terms of sensitivity, costs and timesaving, and has the added advantage of determining the clonal configuration of multiple mutations. We demonstrate that MinION is suitable for employment in the hematology laboratory for detecting BCR-ABL1 KD mutation in Ph+ leukemias.

About 50% of acute myeloid leukemia (AML) patients show the occurrence of non-random chromosome rearrangements. Most of the recurrent karyotypic rearrangements in AML have been defined as distinct disease entities in the 2008 World Health Organization (WHO) classification. In this paper we report an AML case showing a novel t(4;16)(q25;q23.1) rearrangement causing the activation of epidermal growth factor (EGF) and elongation of long-chain fatty acids family member 6 (ELOVL6) genes, rather than the generation of a novel fusion gene.

Myelodysplastic syndromes (MDS) are a heterogeneous group of diseases characterized by ineffective hematopoiesis and an increased risk of evolution to acute myeloid leukemia (AML). In this study, the combination of conventional cytogenetic, FISH studies and molecular techniques allowed us to unveil a novel recurrent t(3;11)(q13;q14) causing the overexpression of the immunoglobulin-like domain-containing receptor (ILDR1) gene. The analysis of gene expression was extended to Refractory Anemia (RA) and Refractory Anemia with excess blasts (RAEB) cases revealing ILDR1 overexpression in 36% of RAEB subgroup. The biological implications of the ILDR1 overexpression in MDS pathogenesis and its potential prognostic significance should be further investigated.

The t(9;22)(q34;q11), generating the Philadelphia chromosome, is found in more than 90% of patients with chronic myelocytic leukemia (CML). Deletions adjacent to the translocation breakpoint on the derivative chromosome 9 have been described by several groups. These studies revealed two primary points: (1) genomic microdeletions were concomitant with the t(9;22) rearrangement; and (2) the location of the deleted sequence was centromeric to ABL and telomeric to BCR genes. We report on a detailed molecular cytogenetic characterization of chromosomal rearrangements in two CML patients bearing a complex variant t(9;22) and insertions of chromosome 22 sequences in 9q34. Our study shows that the location of the deleted sequences was downstream of the ABL gene and that genomic microdeletions were concomitant with the ins(9;22)(q34;q11q11) rearrangement.

The t(8;21)(q22;q22) rearrangement is observed in about 15% of acute myelocitic leukemia (AML) cases, while variant t(8;21) translocations are detected in 6–10% of AML patients positive for the 5′RUNX1/3′CBFA2T1 fusion gene. We report a detailed molecular cytogenetic analysis of a four-way variant t(8;11;16;21)(q22;q14;q12;q22) performed by fluorescence in situ hybridization with specific BAC and PAC clones. The study demonstrated the loss of several megabases belonging to chromosomes 11 and 16 whereas no deletion was detected on der(21). These findings suggest that a precise breakpoint characterization could identify submicroscopic genomic deletions whose meaning remains to be defined.

In the present paper, we report a molecular cytogenetic study of 1q abnormalities associated with t(8;14)(q24;q32) in an adult common B acute lymphoblastic leukemia case with FAB-L2 morphology. The use of appropriate molecular cytogenetic probes allowed us to detect 13 different subclones showing heterogeneous chromosome 1 abnormalities. A complex pattern of rearrangements consisting of translocations, duplications, and inversions was observed. Breakage-fusion-bridge cycle and jumping translocation are hypothesized to have been involved in generating the large number of aberrations we detected.

Recently it has been demonstrated that ten-eleven-translocation-2 (TET2) gene alterations may represent a crucial event in the pathogenesis of various myeloid malignancies. To date, the loss of TET2 function has been solely ascribed to mutations in the gene coding region. In this study, we report a chronic myeloid leukemia (CML) case showing a TET2 single copy partial deletion associated to a t(4;6;11) rearrangement, appearing during the progression of the disease and responsible for a decreased TET2 gene expression. A putative role for TET2 haploinsufficiency in this patient's CML progression is discussed.

Patients affected by monoclonal gammopathy of undetermined significance (MGUS) very rarely develop a myelodysplastic syndrome (MDS). However, it was also demonstrated that MGUS patients had a significantly increased risk of developing MDS compared to the general population. We report a case of 5q-syndrome following a MGUS IgMk with mutation of MYD88 L256P. To our knowledge, this is the first case of del(5q) MDS following MGUS IgMk with the MYD88 L256P mutation in which there is coexistence of the markers of the two clonal diseases, but as an expression of distinct pathological features.