Did You Know?
Interesting fact
The KCNQ1 gene makes part of a potassium channel (IKs) that’s crucial for repolarising the heart after each beat. But that same channel also works in the inner ear’s stria vascularis, where it helps maintain the delicate balance of potassium ions in the endolymph—the fluid that bathes the sensory hair cells of hearing.
When KCNQ1 is mutated, as in LQT1, the impact isn’t always dramatic hearing loss. Instead, subtle deficits often appear only at ultra-high frequencies (12–16 kHz)—well above the range of everyday conversation. Even carriers with just one faulty copy of the gene can show hearing thresholds 5–10 dB higher than average at these frequencies. This makes hearing tests a surprisingly sensitive “whisper” of channel dysfunction, long before the heart’s ECG might reveal a prolonged QT interval.
In other words, the ear can act as an early sensor of cardiac risk, showing how intimately ion channel biology ties the auditory system to the heart’s rhythm. The same KCNQ1 current that allows hair cells to detect a whisper also ensures heart cells can reset in time for the next beat. When it falters, both systems give us clues—sometimes the ears notice before the heart does.
Long QT Type 1
Long QT Type 1 is caused by potassium channels in the heart not operating as they should. Torsades de Pointes, the potentially fatal arrhythmia associated with Long QT Syndrome, is more common in Type 1 but the arrhythmia is also more likely to stop without treatment, making it less fatal. A variety of studies have shown that LQT1 is more frequently triggered by adrenergic stimuli (e.g., physical exertion or emotional stress) compared with other forms of LQTS, particularly by diving and swimming.
Approximately 25–36% of genetically positive patients with LQT1 may have a normal QTc range (defined as<440 ms) without any clinical symptoms at rest. Although these silent mutation-positive patients have a significantly lower risk of life-threatening cardiac events, it should not be assumed that they are safe from future events.
Lethal arrhythmias can still occur in these apparently healthy silent mutation carriers without any warning, especially during emotional stress or physical exertion.
In Long QT Type 1, the loss of function in the IKs channel means fewer potassium ions leave the cell during repolarisation.
When a cell fires, it is like a train pulling into the station; passengers (potassium ions) must get off so it can be cleared and ready for people to get on. The doors on the car are wide and work smoothly, so everyone exits quickly and the train can leave on schedule as the next train is coming.
Many LQTS1 patients are advised to maintain their potassium in the high-normal range (4.5-5.0 mmol/l).
If you look at the train analogy below, imagine the lady with a broken leg has her family waiting outside the train. All her Potassium family is waiting to greet her... She might try and get off quicker! If there's more potassium outside the cell, the electrochemical gradient becomes steeper. Potassium outside the cell increases the drive for the potassium to exit the cell.
In Long QT 1 the IKs channel isn't broken, it's just underpowered. The potassium ions can leave but they do so gradually, not in a rush. The reduced current means they leave the cell too slowly and this lengthens the time it take for the cell to relax (it prolongs the QT).
Imagine someone with a broken leg, or an elderly person with a walker getting off a train in front of you. It's not quick but the train can't leave until you're off so it will sit at the station longer than it should do. However, the next train is due and it won't wait.