Long QT type | Chromosome | Gene | Percentage of genotyped families affected | Ion channel | Typical trigger for syncope/sudden death | Percentage of cardiac events occurring during rest/sleep |
---|---|---|---|---|---|---|
1 | 11 | KCNQ1 (KVLQT1) | 42% | Potassium (Iks), loss of function | Exercise (especially swimming) | 3% |
2 | 7 | KCNH2 (HERG) | 45% | Potassium (Ikr), loss of function | Emotion/loud noise (especially waking from sleep) | 29% |
3 | 3 | SCN5A | 7% | Sodium (INa), gain of function | Rest/sleep | 39% |