Overview
EZH2 encodes a histone methyltransferase that is a component of the polycomb repressive complex 2 (PRC2). This gene is recurrently mutated in both FL and DLBCL and has a common mutation hot spot (Y646) that affects the SET domain.1 EZH2 mutations are one of the defining features of the EZB genetic subgroup of DLBCL.2 Although mutations in EZH2 have been described in some BL patients, they are extremely rare in most BL cohorts that have been sequenced.3,4
Experimental Evidence
Mutations at the main hotspot and some less common hotspots lead to enhanced methylation by PRC2.5
Clinical relevance
A number of small molecule/pharmacologic inhibitors of EZH2 activity have been described.6,7 At least one of these, tazemetostat, has shown benefit in FL.8 Tazemetostat (TAZVERIK) has FDA approval for adult patients with relapsed or refractory (R/R) follicular lymphoma (FL) whose tumors are positive for an EZH2 mutation as detected by an FDA-approved test and who have received at least 2 prior systemic therapies, and for adult patients with R/R FL who have no satisfactory alternative treatment options. Combination therapies including EZH2 inhibitors are also under exploration for DLBCL patients with mutant EZH2.9
Relevance tier by entity
| Entity | Tier | Description |
|---|---|---|
| 1 | High-confidence BL gene | |
| 1 | High-confidence DLBCL gene | |
| 1 | High-confidence FL gene | |
| 1 | High-confidence MZL gene | |
| 1 | High-confidence PMBL gene |
Mutation incidence in large patient cohorts (GAMBL reanalysis)
DLBCL
| Entity | Collection | N | mutated | Incidence | 95% CI |
|---|---|---|---|---|---|
| DLBCL | GAMBL without Reddy | 1,089 | 102 | 0.0937 | [0.0764,0.111] |
| DLBCL | GAMBL with Reddy | 2,088 | 191 | 0.0915 | [0.0791,0.1038] |
| DLBCL | BC | 231 | 32 | 0.1385 | [0.094,0.1831] |
| DLBCL | Dana-Farber | 303 | 19 | 0.0627 | [0.0354,0.09] |
| DLBCL | NCI | 470 | 43 | 0.0915 | [0.0654,0.1176] |
| DLBCL | Reddy | 999 | 89 | 0.0891 | [0.0714,0.1068] |
| DLBCL | DLBCL_ICGC | 85 | 8 | 0.0941 | [0.032,0.1562] |
FL
| pathology | Collection | N | mutated | Incidence | CI |
|---|---|---|---|---|---|
| FL | GAMBL without Crouch | 642 | 143 | 0.2227 | [0.1906,0.2549] |
| FL | GAMBL with Crouch | 1,189 | 291 | 0.2447 | [0.2203,0.2692] |
| FL | BC | 379 | 83 | 0.2190 | [0.1774,0.2606] |
| FL | Kalmbach | 164 | 36 | 0.2195 | [0.1562,0.2829] |
| FL | Crouch | 547 | 148 | 0.2706 | [0.2333,0.3078] |
| FL | FL_ICGC | 99 | 24 | 0.2424 | [0.158,0.3268] |
BL
| pathology | Collection | N | mutated | Incidence | CI |
|---|---|---|---|---|---|
| BL | GAMBL without Panea | 309 | 4 | 0.0128 | [3e-04,0.0254] |
| BL | GAMBL without ICGC/Zhou | 320 | 14 | 0.0194 | [0.0045,0.0344] |
| BL | GAMBL with Panea | 410 | 15 | 0.0168 | [0.0045,0.029] |
| BL | BLGSP | 219 | 3 | 0.0137 | [0,0.0291] |
| BL | Zhou/ICGC | 90 | 1 | 0.0111 | [0,0.0328] |
| BL | Panea | 101 | 11 | 0.1089 | [0.0482,0.1697] |
Mutation pattern and selective pressure estimates
| Entity | Missense dN/dS | Nonsense dN/dS | Q value |
|---|---|---|---|
| BL | 3.5147 | 0.0000 | 1 |
| FL | 18.8751 | 0.0000 | 0 |
| DLBCL | 5.6322 | 0.3606 | 0 |
EZH2 Hotspots
| Chromosome | Coordinate (hg19) | ref>alt | HGVSp |
|---|---|---|---|
| chr7 | 148508745 | T>C | N640S |
| chr7 | 148508740 | A>G | F642L |
| chr7 | 148508728 | A>T | Y646N |
| chr7 | 148508728 | A>G | Y646H |
| chr7 | 148508727 | T>G | Y646S |
| chr7 | 148508727 | T>C | Y646C |
| chr7 | 148508727 | T>A | Y646F |
| chr7 | 148506466 | TG>GC | A682G |
| chr7 | 148506467 | G>C | A682G |
| chr7 | 148506437 | GC>AA | A692L |
| chr7 | 148506437 | G>A | A692V |
Visualizations
Protein
View coding variants in ProteinPaint hg19 or hg38
Genome
View all variants in GenomePaint hg19 or hg38
Expression
Representative Mutations
BL
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