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Translocations Activating IRF4 Identify a Subtype of Germinal-Center-Derived B-cell Lymphoma Affecting Predominantly Children and Young Adults

ABSTRACT: Background: Germinal center B-cell (GCB) lymphomas are common in children and adults. The prognosis strongly depends on age. Subgroups of GCB-lymphomas are characterized by chromosomal translocations affecting immunoglobulin (IG) loci leading to oncogene deregulation. Methods: Novel IG translocation partners were cloned within the network “Molecular Mechanisms in Malignant Lymphomas” (MMML) by long-distance inverse polymerase chain reaction. Mature aggressive B-cell lymphomas from the MMML as well as pediatric and adult lymphoma trials were analyzed by fluorescence in situ hybridization (FISH) and immunhistochemistry. Data from 438 MMML cases characterized by gene expression profiling were mined. Results: Cloning of unknown IG partners identified a t(6;14)(p25;q32) juxtaposing the IRF4 oncogene with the IGH-locus as novel recurrent aberration in GCB lymphoma. FISH analyses of 427 mature B-cell lymphomas for IRF4 translocations revealed 20 IG/IRF4 positive lymphomas (17 IGH/IRF4, 2 IGL/IRF4, 1 IGΚ/IRF4). IG/IRF4-positive lymphomas were predominantly GCB-type diffuse large B-cell lymphomas (DLBCL) or follicular lymphoma grade 3, shared overexpression of IRF4/MUM1 and BCL6 and lacked PRDM1/BLIMP1 expression and t(14;18)/BCL2 breaks. BCL6 aberrations were common. The gene expression profile of IG/IRF4-positive lymphomas was different from other subtypes of DLBCL and a classifier for IG/IRF4 positivity containing 27 genes allowed prediction of 3 additional MMML IG/IRF4-positive cases subsequently proven by FISH. IG/IRF4-positivity was associated with a favorable outcome likely due to significant enrichment of IG/IRF4-positive lymphomas in childhood and young adulthood. Conclusions: Our results suggest IRF4 translocations to be primary genetic alterations in a novel molecularly defined subset of GC-derived lymphomas predominantly affecting children.

ORGANISM(S): Homo sapiens

PROVIDER: GSE22470 | GEO | 2011/06/24

SECONDARY ACCESSION(S): PRJNA128585

REPOSITORIES: GEO

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Translocations Activating IRF4 Identify a Subtype of Germinal-Center-Derived B-cell Lymphoma Affecting Predominantly Children and Young Adults

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