NPM1 Deletion Is Associated with Gross Chromosomal Rearrangements in Leukemia |
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| Authors: | Roberta La Starza Caterina Matteucci Paolo Gorello Lucia Brandimarte Valentina Pierini Barbara Crescenzi Valeria Nofrini Roberto Rosati Enrico Gottardi Giuseppe Saglio Antonella Santucci Laura Berchicci Francesco Arcioni Brunangelo Falini Massimo Fabrizio Martelli Constantina Sambani Anna Aventin Cristina Mecucci |
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| Institution: | 1. Hematology, University of Perugia, Perugia, Italy.; 2. Instituto Pelé Pequeno Principe, Faculdades Pequeno Principe, Curitiba, Brazil.; 3. Department of Clinical and Biological Sciences, University of Turin, Turin, Italy.; 4. Demokritos Cancer Centre, Athens, Greece.; 5. Servei de Hematologia, Hospital De La Santa Creu I Sant Pau, Barcelona, Spain.;University of Barcelona, Spain |
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| Abstract: | Background
NPM1 gene at chromosome 5q35 is involved in recurrent translocations in leukemia and lymphoma. It also undergoes mutations in 60% of adult acute myeloid leukemia (AML) cases with normal karyotype. The incidence and significance of NPM1 deletion in human leukemia have not been elucidated.Methodology and Principal FindingsBone marrow samples from 145 patients with myelodysplastic syndromes (MDS) and AML were included in this study. Cytogenetically 43 cases had isolated 5q-, 84 cases had 5q- plus other changes and 18 cases had complex karyotype without 5q deletion. FISH and direct sequencing investigated the NPM1 gene. NPM1 deletion was an uncommon event in the “5q- syndrome” but occurred in over 40% of cases with high risk MDS/AML with complex karyotypes and 5q loss. It originated from large 5q chromosome deletions. Simultaneous exon 12 mutations were never found. NPM1 gene status was related to the pattern of complex cytogenetic aberrations. NPM1 haploinsufficiency was significantly associated with monosomies (p<0.001) and gross chromosomal rearrangements, i.e., markers, rings, and double minutes (p<0.001), while NPM1 disomy was associated with structural changes (p = 0.013). Interestingly, in complex karyotypes with 5q- TP53 deletion and/or mutations are not specifically associated with NPM1 deletion.Conclusions and Significance
NPM1/5q35 deletion is a consistent event in MDS/AML with a 5q-/-5 in complex karyotypes. NPM1 deletion and NPM1 exon 12 mutations appear to be mutually exclusive and are associated with two distinct cytogenetic subsets of MDS and AML. |
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