Summary of most frequent kit and pdgfra mutations in sporadic gastrointestinal stromal tumours
| Gene | Exon | Frequency (%) | Mutation | Remarks |
|---|---|---|---|---|
| kit | 11 | 20–60 | Deletion–insertion 550–561 | Deletion is often associated with bad prognosis. Good response to imatinib |
| Point mutations 557, 559, 560, 576 | ||||
| Internal tandem duplications beyond 570 (3′ end) | ||||
| 9 | 10–15 | Duplication–insertion 501–502 | Malignant behaviour Small intestine Intermediate response to imatinib | |
| 13 | <5 | Point mutation 642 | Bad response to imatinib | |
| 17 | Rare (<1) | Point mutation 820 | Bad response to imatinib | |
| pdgfra | 12 | Roughly 1 | Point mutation 561 | Good response to imatinib |
| Deletion–insertion 560–571 | ||||
| Insertion 582–586 | ||||
| 14 | <0.5 | Point mutation 659 | ||
| 18 | 2–3 | Point mutation 842 | Mutation 842 (D842V) resistant to imatinib Other sensitive | |
| Deletion–substitution 842–847 |