MSI and IHC results among probands who had MSI and/or IHC testing
| Molecular tumour characteristics | Total | No mutation | MLH1 | MSH2 | MSH6 |
| N (%) | N (%) | N (%) | N (%) | N (%) | |
| Total | 1651 (100) | 1412 (85.5) | 90 (5.5) | 125 (7.6) | 24 (1.5) |
| MSI result | |||||
| Stable/low* | 819 (59.0) | 810 (65.8) | 2 (3.2) | 6 (7.9) | 1 (6.2) |
| High | 568 (41.0) | 422 (34.2) | 61 (96.8) | 70 (92.1) | 15 (93.8) |
| Total | 1387 (100) | 1232 (100) | 63 (100) | 76 (100) | 16 (100) |
| IHC result† | |||||
| MLH1 (N=1576) | 366 (23.2) | 288/1349 (21.3) | 78/84‡ (92.8) | 0 (0) | 0 (0) |
| MSH2 (N=1592) | 170 (10.7) | 54/1360 (4.0) | 0 (0) | 116/121§ (95.9) | 0 (0) |
| MSH6 (N=1448) | 165 (11.4) | 53/1234 (4.3) | 0 (0) | 95/108 (87.9) | 17/24 (70.8) |
| PMS2 (N=908) | 257 (28.3) | 196/748 (26.2) | 61/62 (98.4) | 0 (0) | 0 (0) |
↵* MSI-low: total=335, no Mutation=330, MLH1=0, MSH2=5, MSH6=0.
↵† Abnormal IHC results shown (based on abnormal versus normal/inconclusive categories).
↵‡ Of 90 MLH1 mutation carriers, 84 had IHC testing for MLH1 protein expression.
↵§ Of 125 MSH2 mutation carriers, 121 had IHC testing for MSH2 protein expression.
IHC, immunohistochemistry; MSI, microsatellite instability.