EZH2 mutations were frequently associated with the presence of BCL2 rearrangement (BCL2-R) in both the FL (28% of BCL-R cases versus 0% of BCL2-WT cases, p<0.05) and GCB-DLBCL groups (33% of BCL2-R cases versus 4% of BCL2-WT cases, p<0.04), and across all lymphoma types excluding BL (27% of BCL2-R cases versus 3% of BCL2-WT cases, p<0.003).
These mutations, which result in the replacement of a single tyrosine in the SET domain of the EZH2 protein (Tyr641), occur in 21.7% of GCB DLBCLs and 7.2% of FLs and are absent from ABC DLBCLs.
GCET2 (Germinal centre B-cell expressed transcript 2; also named HGAL) is a newly cloned gene that has been shown to be a useful marker for germinal centre (GC) B cells and GC B-cell derived malignancies, including follicular lymphomas and germinal centre B cell-like diffuse large B-cell lymphomas (GCB-DLBCLs), and is a useful prognosticator for DLBCLs.