Chromosomal abnormalities in chronic lymphocytic leukemia (CLL) are detected in up to 80% of patients. Among them, deletions of 11q, 13q, 17p, and trisomy 12 have a known prognostic value and play an important role in CLL pathogenesis and evolution, determining patients outcome and therapeutic strategies. Standard methods used to identify these genomic aberrations include both conventional G-banding cytogenetics (CGC) and fluorescencein situhybridization (FISH). Although FISH analyses have been implemented as the gold standard, CGC allows the identification of chromosomal translocations and complex karyotypes, the latest associated with poor outcome. Genomic arrays have a higher resolution that allows the detection of cryptic abnormalities, although these have not been fully implemented in routine laboratories. In the last years, next generation sequencing (NGS) methods have identified a wide range of gene mutations (e.g.,TP53, NOTCH1, SF3B1,andBIRC3) which have improved our knowledge about CLL development, allowing us to refine both the prognostic subgroups and better therapeutic strategies. Clonal evolution has also recently arisen as a key point in CLL, integrating cytogenetic alterations and mutations in a dynamic model that improve our understanding about its clinical course and relapse.

Sézary syndrome is a leukemic form of cutaneous T-cell lymphoma with an aggressive clinical course. The genetic etiology of the disease is poorly understood, with chromosomal abnormalities and mutations in some genes being involved in the disease. The goal of our study was to understand the genetic basis of the disease by looking for driver gene mutations and fusion genes in 15 erythrodermic patients with circulating Sézary cells, 14 of them fulfilling the diagnostic criteria of Sézary syndrome. We have discovered genes that could be involved in the pathogenesis of Sézary syndrome. Some of the genes that are affected by somatic point mutations include ITPR1, ITPR2, DSC1, RIPK2, IL6, and RAG2, with some of them mutated in more than one patient. We observed several somatic copy number variations shared between patients, including deletions and duplications of large segments of chromosome 17. Genes with potential function in the T-cell receptor signaling pathway and tumorigenesis were disrupted in Sézary syndrome patients, for example, CBLB, RASA2, BCL7C, RAMP3, TBRG4, and DAD1. Furthermore, we discovered several fusion events of interest involving RASA2, NFKB2, BCR, FASN, ZEB1, TYK2, and SGMS1. Our work has implications for the development of potential therapeutic approaches for this aggressive disease.

Novel treatments in chronic lymphocytic leukemia (CLL) have generated interest regarding the clinical impact of genomic complexity, currently assessed by chromosome banding analysis (CBA) and chromosomal microarray analysis (CMA). Optical genome mapping (OGM), a novel technique based on imaging of long DNA molecules labeled at specific sites, allows the identification of multiple cytogenetic abnormalities in a single test. We aimed to determine whether OGM is a suitable alternative to cytogenomic assessment in CLL, especially focused on genomic complexity. Cytogenomic OGM aberrations from 42 patients were compared with CBA, FISH, and CMA information. Clinical–biological characteristics and time to first treatment (TTFT) were analyzed according to the complexity detected by OGM. Globally, OGM identified 90.3% of the known alterations (279/309). Discordances were mainly found in (peri-)centromeric or telomeric regions or subclonal aberrations (<15–20%). OGM underscored additional abnormalities, providing novel structural information on known aberrations in 55% of patients. Regarding genomic complexity, the number of OGM abnormalities had better accuracy in predicting TTFT than current methods (C-index: 0.696, 0.602, 0.661 by OGM, CBA, and CMA, respectively). A cut-off of ≥10 alterations defined a complex OGM group (C-OGM, n = 12), which included 11/14 patients with ≥5 abnormalities by CBA/CMA and one patient with chromothripsis (Kappa index = 0.778; p < 0.001). Moreover, C-OGM displayed enrichment of TP53 abnormalities (58.3% vs. 3.3%, p < 0.001) and a significantly shorter TTFT (median: 2 vs. 43 months, p = 0.014). OGM is a robust technology for implementation in the routine management of CLL patients, although further studies are required to define standard genomic complexity criteria.

Patients with chronic lymphocytic leukemia and complex karyotype show an adverse outcome even in absence of TP53/ATM FISH deletions Patients with chronic lymphocytic leukemia and complex karyotype show an adverse outcome even in absence of TP53/ATM FISH deletions

Oligomonocytic chronic myelomonocytic leukemia (OM-CMML) is defined as those myelodysplastic syndromes (MDSs) or myelodysplastic/myeloproliferative neoplasms, unclassifiable with relative monocytosis (≥10% monocytes) and a monocyte count of 0.5 to 94% classical monocytes (MO1s) and CD56 and/or CD2 positivity in peripheral blood monocytes, was similar to overt CMML. The MO1 percentage >94% method showed high accuracy for predicting CMML diagnosis (sensitivity, 90.7%; specificity, 92.2%), even when considering OM-CMML as a subtype of CMML (sensitivity, 84.9%; specificity, 92.1%) in our series of 233 patients (39 OM-CMML, 54 CMML, 23 MDS, and 15 myeloproliferative neoplasms with monocytosis and 102 reactive monocytosis). These results support the consideration of OM-CMML as a distinctive subtype of CMML.