Cryptic NUP214-ABL1 fusion with complex karyotype, episomes and intra-tumor genetic heterogeneity in a T-cell lymphoblastic lymphoma

T-lymphoblastic lymphoma (T-LBL) is a rare and aggressive form of non-Hodgkin’s lymphoma and little is known about their molecular background. However, complex karyotypes were already related to this group of malignancy and associated with poor outcome. Here, we describe a 17-year-old female being diagnosed with T-LBL and a normal karyotype after standard G-banding with trypsin-Giemsa (GTG)-banding. However, further analyses including high-resolution molecular approaches, array-comparative genomic hybridization (aCGH), multiplex ligation-dependent probe amplification, fluorescence in situ hybridization and multicolor chromosome banding revealed a cryptic complex karyotype, NUP214-ABL1 gene fusion, episomes and intra-tumor genetic heterogeneity. In addition, homozygous loss of CDKN2A, as well as amplification of oncogene TLX1 (HOX11) were detected. Actually, NUP214-ABL1 fusion gene replicated autonomously in this case as episomes. Overall, highly amplification of NUP214-ABL1 fusion gene defines possibly a new subgroup of T-LBL patients which accordingly could benefit from treatment with tyrosine kinase inhibitors. As episomes are missed in standard karyotyping aCGH should be performed routinely in T-LBL to possibly detect more of such cases

Does positioning of chromosomes 8 and 21 in interphase drive t(8;21) in acute myelogenous leukemia?

The impact of chromosome architecture in the formation of chromosome aberrations is a recent finding of interphase directed molecular cytogenetic studies. There evidence was provided that disease specific chromosomal translocations could be due to tissue specific genomic organization. In a recent small pilot study using three-dimensional interphase fluorescence in situ hybridization, we showed that there might be a specific chromosome positioning in myeloid bone marrow cells, i.e. a co-localization of chromosomes 8 and 21. Here we could substantiate this finding in overall 21 studied cases with acute myeloid leukemia (AML) that there is even a co-localization of the genes AML1 and ETO. This finding led to the suggestion that a specific interphase architecture of myeloid bone marrow cells might promote the typical t(8;21)(q22;q22) leading to AML-M2

A unique set of complex chromosomal abnormalities in an infant with myeloid leukemia associated with Down syndrome

Abstract Background Children with Down syndrome (DS) have an enhanced risk of developing acute leukemia, with the most common subtype being acute megakaryoblastic leukemia (AMKL). Myeloid leukemia in Down syndrome (ML-DS) is considered a disease with distinct clinical and biological features. There are few studies focusing on the clonal cytogenetic changes during evolution of ML-DS. Case presentation Here, we describe a complex karyotype involving a previously unreported set of chromosomal abnormalities acquired during progression of ML-DS in an infant boy: derivative der(1)t(1;15)(q24;q23), translocation t(4;5)(q26;q33) and derivative der(15)t(7;15)(p21;q23). Different molecular cytogenetic probes and probesets including whole chromosome painting (WCP) and locus specific probes, as well as, multicolor-FISH and multicolor chromosome banding (MCB) were performed in order to characterize the chromosomal abnormalities involved in this complex karyotype. The patient was treated according to the acute myeloid leukemia-Berlin-Frankfurt-Munich-2004 (AML-BFM 2004) treatment protocol for patients with Down syndrome; however, he experienced a poor clinical outcome. Conclusion The molecular cytogenetic studies performed, allowed the characterization of novel chromosomal abnormalities in ML-DS and possible candidate genes involved in the leukemogenic process. Our findings suggest that the complex karyotype described here was associated with the poor prognosis