Introduction: Diffuse large B-cell lymphomas (DLBCLs) are phenotypically and genetically heterogeneous. Gene-expression profiling has identified two subgroups of DLBCL; activated B-cell–like (ABC) and germinal-center Bcell–like (GCB) according to cell of origin. Diagnosis relies on a combination of morphologic findings (peripheral blood, bone marrow, or lymph node), immunohistochemistry, immunophenotyping, cytogenetics, fluorescence in situ hybridization (FISH) and molecular genetics. Enhancer of zeste homolog 2 (EZH2) is the catalytic subunit of the polycomb repressive complex 2 (PRC2) which implements transcriptional repression by trimethylation at lysine 27 of histone H3 (H3K27me3). It is important for normal immunoglobulin VDJ recombination in pre-B cells. EZH2 (Y641) mutations result in increased EZH2 stability and increased H3K27me3 activity, resulting in the repression of tumor suppressor genes. Its catalytic activity is closely correlated with tumor aggressiveness, drug resistance, and poor prognosis. Here, we studied 50 DLBCL biopsy samples using chain termination sequencing.

Aim: The aim of the study was to study the mutational status of enhancer of zeste homolog 2 (EZH2) gene tyrosine 641and its relation with different clinicopathological parameters in DLBCL patients.