Table 1.
Main cardiac ion currents involved in QT abnormalities: Genes, Channels, LQTS and SQTS.
| Gene-α Subunit | Gene- β Subunit | Current Name | Repolarization | Loss of Function | Gain of Function |
|---|---|---|---|---|---|
| KCND3-Kv4.3 | KChIP2.2 | Ito, f Transient outward or rapid partial repolarizing |
Notch of the action potential | SQTS Brugada |
|
| KCNQ1-KvLQT1-Kv7.1 | KCNE1/Mink | IKs Slowly activating delayed rectifier |
Repolarization | LQTS1 LQTS + reactive hypoglycemia + low serum K+ |
SQTS1 |
| KCNH2/hERG-Kv11.1 | KCNE2/MiRP1 | IKr Rapidly activating delayed rectifier |
Repolarization | LQTS2 | SQTS2 |
| KCNJ2- Kir2.1 | IK1 Inwardly rectifying |
Terminal phase diastolic membrane potential/maintains negative resting potential | LQTS Andersen-Tawil syndrome |
SQTS3 | |
| SCN5A-Nav1.5 | SCN1B-Navβ1 | Nav1.5 | Fast depolarization (phase 0) of the action potential, | Brugada | LQTS3 |