t(10;12)(q24;q15): A new cytogenetic marker in hematological malignancies.

Cytogenetic studies have played a crucial role in the discovery of genes involved in several diseases. In the field of oncohematology, cytogenetics is still necessary for the classification and prognosis of many diseases. Here we report a new recurrent chromosome translocation, t(10;12)(q24;q15), in two patients with different hematological malignancies: myelodysplastic syndrome with excess blasts (MDS-EB), and myelofibrosis (MF) secondary to essential thrombocythemia (ET). The chromosome alteration was observed as a sole karyotype change in the patient with MDS-EB, both at the initial diagnosis and following progression to MDS-EB2. A putative HMGA2-KLLN rearrangement by RNA-sequencing was detected in this patient. The patient with ET, had a normal karyotype at diagnosis and the t(10;12)(q24;q15) translocation emerged as a sole cytogenetic alteration after transformation, and when MF was evident. We reviewed the literature to determine whether this chromosome abnormality had previously been described in other hematological patients and found two cases: an aggressive T-cell lymphoblastic lymphoma (T-LBL) and a case of transformed chronic myeloproliferative syndrome (CMS), in both of which t(10;12)(q24;q15) was also the only karyotype change. The clinical evolution of all four cases suggested that t(10;12)(q24;q15) is associated with a poor outcome in oncohematological patients.

Acute lymphoblastic leukemia with e1a3 BCR/ABL fusion protein. A report of two cases.

B Acute Lymphoblastic leukemia (B-ALL) with Philadelphia chromosome (Ph') is a neoplasm of lymphoblast committed to the B cell lineage. The clinical presentation of B-ALL Ph'+ is similar to B-ALL, but is more common in adults than in children. The e1a3 rare variant is produced by the fusion of BCR exon 1 to ABL exon 3. The presence of this translocation has been associated with good disease outcome for chronic myeloid leukemia in a very small series of only 5 cases; there is no such evidence for B-ALL. We report two new cases of B-ALL Ph+ with the rare e1a3 fusion transcript. The e1a3 and e1a2 (p190) transcripts have been reported to have a similar molecular weight and probably a similar clinical profile, thus in these cases the presence of e1a3 was associated with extramedullary infiltration and disease acceleration.

Genetics of lymphocytes influences the emergence of second cancer in chronic lymphocytic leukemia.

BACKGROUND: Patients affected by chronic lymphocytic leukemia (CLL) have an increased risk of developing a second cancer. There is not a definitive explanation for this phenomenon, although some hypotheses have been postulated. The aim of the present work was to assess the presence of second cancer in untreated patients with CLL who were cytogenetically characterized, and secondly to investigate if there is a correlation between the genetics of CLL and the emergence of second cancer. PATIENTS AND METHODS: We performed conventional cytogenetics and Fluorescent in situ hybridization analyses in a series of 106 patients. RESULTS: We observed that nearly 8% of cases developed second cancer, mostly epithelial tumors. The majority of them presented two common features, del(13)(q14.3) and the presence of at least two genetic alterations. CONCLUSION: We suggest that the genetic background of CLL, particularly the presence of several genetic alterations, influences the emergence of second cancer in patients affected by CLL.

Structural rearrangements of trisomies are a risk marker of clinical progression in hyperdiploid multiple myeloma.

BACKGROUND: Hyperdiploid multiple myeloma (HMM) is being characterized by the presence of several trisomies and a low incidence of immunoglobulin heavy chain rearrangements. It has not well defined what specific steps are associated with disease progression. We present two patients that showed some primary trisomies rearranged as a step of cytogenetic and clinical progression. This prompted us to review cytogenetic results from all patients referred to our hospital to assess the importance of this phenomenon in HMM. PATIENTS AND METHODS: We carried out conventional cytogenetics in all patients. In four cases we also performed spectral karyotype (SKY) and arm-specific chromosome painting (ASP). RESULTS: We demonstrate that in two patients some primary trisomies became along the disease course structurally altered and this coincided with clinical progression. We observed this phenomenon in more than 60% of HMM cases diagnosed at our laboratory. CONCLUSION: We propose structural rearrangements of trisomies as a biological marker of progression in HMM.

dup(1)(q21q32) as a sole cytogenetic event is associated to a leukemic transformation in myelodysplastic syndromes.

Duplication of the long arm of chromosome 1 (1q) has been detected accompanied with other chromosome abnormalities in Myelodysplastic Syndromes (MDS). However, as a sole karyotypic change, it is rarely observed. We present here two patients affected of a MDS that showed a dup(1)(q21q32) as a sole cytogenetic change in their bone marrow cells. Complementary methodologies confirmed the duplication of chromosome 1q and, did not show additional cryptic chromosome abnormalities. One patient acquired a secondary trisomy 8 and the other one progressed toward an acute leukemia with no additional cytogenetic alterations.

Mutations in TBX1 genocopy the 22q11.2 deletion and duplication syndromes: a new susceptibility factor for mental retardation.

A screen for TBX1 gene mutations identified two mutations in patients with some features compatible with the 22q11.2-deletion syndrome but with no deletions. One is a de novo missense mutation and the other is a 5' untranslated region (5'UTR) C>T change that affects a nucleotide with a remarkable trans-species conservation. Computer modelling shows that the 5'UTR change is likely to affect the mRNA structure and in vitro translation experiments demonstrate that it produces a twofold increase in translation efficiency. Recently, duplications in the 22q11.2 region were reported in patients referred for fragile-X determination because of cognitive and behavioural problems. Because the 5'UTR nucleotide change may be a functional equivalent of a duplication of the TBX1 gene, we decided to screen 200 patients who had been referred for fragile-X determination and 400 healthy control individuals. As a result, we found the 5'UTR mutation to be present in three patients with mental retardation or behavioural problems and absent in control individuals of the same ethnic background. This observation suggests that it may be reasonable to screen for such mutation among patients with unspecific cognitive deficits and we provide an easy and quick way to do it with an amplification refractory mutation system (ARMS) approach. To our knowledge, this is the first human mutation showing that TBX1 is a candidate causing mental retardation associated with the 22q11.2 duplication syndrome.

Genomic imbalances and patterns of karyotypic variability in mantle-cell lymphoma cell lines.

Mantle-cell lymphoma (MCL) is genetically characterized by 11q13 chromosomal translocations involving the CCND1 gene. We have characterized five MCL cell lines, JVM-2, GRANTA-519, REC-1, JEKO-1, and NCEB-1, combining metaphase and array comparative genomic hybridization, multicolor-FISH, and molecular analysis. Our results revealed common gained regions at 2p14, 9q31.2-qter, 11q13.1-q21, 13q14-q21.2, 13q34-qter and 18q21.1-q22.1, and losses at 1p21.2-p31.1, 2p11.2, 8p21.2-pter, 9p21.3-pter, 11q23.3-qter, 17p11.2-pter, and 17q21.2-q22.2. All cell lines except JVM-2, displayed moderate or high numerical chromosome instability. In addition, an ongoing level of chromosome rearrangements was observed in REC-1. Surprisingly, NCEB-1 carried several stable mouse chromosomes and showed expression of both human and murine bcl-2 protein. Our findings indicate that these cell lines represent three patterns of chromosome evolution in MCL and may be useful to understand the pathogenesis of this neoplasm.

Common pattern of unusual chromosome abnormalities in hereditary papillary renal carcinoma.

In this study, we summarized cytogenetic and comparative genomic hybridization (CGH) results, mutation analysis of the MET gene, and immunohistochemistry results of tumors from three patients in the same family who were affected by hereditary papillary renal carcinoma (HPRC). All three patients showed germline mutations in the tyrosine kinase domain of the MET proto-oncogene, and developed bilateral and multiple papillary renal tumors. DNA mutation analysis showed an increased dosage of the mutant allele in six tumors from two patients but not in two tumors from the third patient. In addition to the recurrent chromosomal alterations found in papillary renal carcinomas, cytogenetic analyses revealed the presence of an identical chromosomal translocation, t(2;15)(q13;p11), in two different tumors from the same patient. Moreover, the same pattern of autosomal trisomies (+7, +12, +13, +17) was detected by CGH analysis in tumors from different siblings. Taking into account that the presence of an identical structural chromosomal aberration in two tumors and the gain of chromosome 13 are unusual chromosomal changes in this type of tumor, we can conclude that our results confirm those of other authors and suggest that the genetic predisposition to HPRC might predispose the acquisition of genomic alterations in specific chromosomes or chromosomal regions.

Genetic diagnosis by comparative genomic hybridization in adult de novo acute myelocytic leukemia.

A total of 127 adult de novo acute myelocytic leukemia (AML) patients were analyzed by comparative genomic hybridization (CGH) at diagnosis. Conventional cytogenetic analysis (CCA) showed a normal karyotype in 45 cases and an abnormal karyotype in 56 cases; in the remaining cases, CCA either failed to yield sufficient metaphase cells (19/26) or was not done (7/26). Abnormal CGH profiles were identified in 39 patients (30.7%). DNA copy number losses (61%) were high compared to gains (39%), whereas partial chromosome changes (76%) were more common than whole chromosomes changes (24%). Recurrent losses were detected on chromosomes 7, 5q (comprising bands 5q15 to 5q33), 7q (7q32 approximately q36), 16q (16q13 approximately q21), and 17p, and gains were detected on chromosomes 8, 22, and 3q (comprising bands 3q26.1 approximately q27). Furthermore, distinct amplifications were identified in chromosome regions 21q, 13q12 approximately q13, and 13q21.1. No cryptic recurrent chromosomal imbalances were identified by CGH in cases with normal karyotypes. The concordance between CGH results and CCA was 72.5%. In the remaining cases, CGH gave additional information compared to CCA (20%) and partially failed to identify the alterations previously detected by CCA (7.5%). The majority of discrepancies arose from the limitations of the CGH technique, such as insensitivity to detect unbalanced chromosomal changes when occurring in a low proportion of cells. CGH increased the detection of unbalanced chromosomal alterations and allowed precise defining of partial or uncharacterized cytogenetical abnormalities. Application of the CGH technique is thus a useful complementary diagnostic tool for CCA in de novo AML cases with abnormal karyotypes or with unsuccessful cytogenetics.

Analysis of kidney tumors by comparative genomic hybridization and conventional cytogenetics.

Comparative genomic hybridization (CGH) and conventional cytogenetic karyotyping were used to screen for losses and gains of DNA sequences along chromosomes in ten renal tumors (RCC) of different histologic types (clear-cell RCC, papillary RCC, and one oncocytoma). Loss of 3p was the most common change in clear-cell RCC. All papillary tumors, either adenomas or carcinomas revealed gains of chromosomes 7 and 17q without limitation to size and grade. Homozygotic loss of the pseudoautosomal Xp or Yp region was detected in three RCC tumors. A dicentric (Y;14) was present as the sole chromosome abnormality in the oncocytoma. Both techniques showed concordant results in tumors with homogeneous karyotype. However, in tumors with several composite clones some discrepancies were observed, especially in cases of clear-cell RCC where chromosomal abnormalities present in a low number of metaphases could not be detected by CGH.