Array-based comparative genomic hybridization (arrayCGH) studies in chronic lymphocytic leukemia (CLL) have revealed novel recurrent chromosomal imbalances, such as a gain of chromosome 2p. However, a detailed cytogenetic analysis of the 2p gain region has not been elucidated. Here, we present cytogenetic and molecular cytogenetic analysis of 16 such cases selected from a group of 200 patients with CLL based on CGH and/or arrayCGH data. We revealed significant heterogeneity of the region of gain on 2p in CLL, including a new recurrent aberration: the dicentric chromosome, dic(2;18). In our cases, the region of gain involved three genes (MYCN, REL, and ALK) and was associated with an unmutated IgVH status in 14 out of 16 cases. We consider this aberration clinically important in CLL and suggest that an examination of the gene(s) located in region of gain should be included in the routine fluorescence in situ hybridization screening method used for patients with CLL.

embedded tissue sections. As positive controls, normal testis and bone marrow biopsies from patients with mastocytosis were used. Sections were stained according to the manufacturer's recommendations, and IHC results were visualized using the En Vision system (Dako Denmark A/S).

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Hepatosplenic T-cell lymphoma (HSTL) is an aggressive lymphoma cytogenetically characterized by isochromosome 7q [i(7)(q10)], of which the molecular consequences remain unknown. We report here results of an integrative genomic and transcriptomic (expression microarray and RNA-sequencing) study of six i(7)(q10)-positive HSTL cases, including HSTL-derived cell line (DERL-2), and three cases with ring 7 [r(7)], the recently identified rare variant aberration. Using high resolution array CGH, we profiled all cases and mapped the common deleted region (CDR) at 7p22.1p14.1 (34.88 Mb; 3506316-38406226 bp) and the common gained region (CGR) at 7q22.11q31.1 (38.77 Mb; 86259620–124892276 bp). Interestingly, CDR spans a smaller region of 13 Mb (86259620–99271246 bp) constantly amplified in cases with r(7). In addition, we found that TCRG (7p14.1) and TCRB (7q32) are involved in formation of r(7), which seems to be a byproduct of illegitimate somatic rearrangement of both loci. Further transcriptomic analysis has not identified any CDR-related candidate tumor suppressor gene. Instead, loss of 7p22.1p14.1 correlated with an enhanced expression of CHN2 (7p14.1) and the encoded β2-chimerin. Gain and amplification of 7q22.11q31.1 are associated with an increased expression of several genes postulated to be implicated in cancer, including RUNDC3B, PPP1R9A and ABCB1, a known multidrug resistance gene. RNA-sequencing did not identify any disease-defining mutation or gene fusion. Thus, chromosome 7 imbalances remain the only driver events detected in this tumor. We hypothesize that the Δ7p22.1p14.1-associated enhanced expression of CHN2/β2-chimerin leads to downmodulation of the NFAT pathway and a proliferative response, while upregulation of the CGR-related genes provides growth advantage for neoplastic δγT-cells and underlies their intrinsic chemoresistance. Finally, our study confirms the previously described gene expression profile of HSTL and identifies a set of 24 genes, including three located on chromosome 7 (CHN2, ABCB1 and PPP1R9A), distinguishing HSTL from other malignancies.

The simultaneous occurrence of polycythemia vera (PV) and chronic lymphocytic leukemia (CLL) is a rare event that offers a possibility to study their common origin. PV originates from self-renewing hematopoietic stem cells (HSC) with both lymphoid and myeloid potential(1–3). It has been reported that CLL also originates from self-renewing HSC with a potential for both lymphoid and myeloid differentiation(4, 5). We report 3 females with concomitant CLL and PV whose X-chromosome inactivation patterns of the neoplastic cells revealed that granulocytes/platelets and B-lymphocytes used different X-chromosome alleles. These data indicate that both PV and CLL have arisen independently and from different HSC.