Long QT syndrome
Cardiology section
Long QT syndrome (LQTS) is a cardiac disorder characterized by prolongation of the QT interval on the electrocardiogram (ECG). The QT interval represents the time it takes for the heart to repolarize, or reset, after each
heartbeat. Prolongation of the QT interval can lead to a predisposition to a specific type of ventricular arrhythmia called Torsades de Pointes (TdP), which can result in syncope (fainting), seizures, or sudden cardiac arrest.
ABOUT LONG QT SYNDROM
UNDERSTANDING Long QT Syndrome
Long QT Syndrome (LQTS): Causes and Subtypes
Long QT Syndrome (LQTS) can be either inherited or acquired. Inherited LQTS is primarily caused by mutations in genes encoding cardiac ion channels, disrupting normal repolarization processes, leading to QT prolongation and arrhythmias.
Acquired LQTS can result from certain medications, electrolyte imbalances, or other medical conditions. Several subtypes of LQTS are associated with mutations in different genes.
Mutations in at least 15 genes have been linked to LQTS. These genes encode ion channels or channel-associated proteins involved in cardiac repolarization. The most common genes associated with LQTS include:
KCNQ1 (Potassium Voltage-Gated Channel Subfamily Q Member 1):
KCNH2 (Potassium Voltage-Gated Channel Subfamily H Member 2):
SCN5A (Sodium Voltage-Gated Channel Alpha Subunit 5):
KCNE1 (Potassium Voltage-Gated Channel Subfamily E Regulatory Subunit 1)
KCNE2 (Potassium Voltage-Gated Channel Subfamily E Regulatory Subunit 2):
ANK2 (Ankyrin 2):
CACNA1C (Calcium Voltage-Gated Channel Subunit Alpha1 C):
These genes play critical roles in cardiac repolarization and the regulation of the cardiac action potential.
Mutations in these genes disrupt normal ion channel function, leading to prolonged QT intervals on the electrocardiogram (ECG) and an increased risk of life-threatening arrhythmias such as Torsades de Pointes (TdP) and sudden cardiac death. Genetic testing can identify specific mutations associated with LQTS and guide risk assessment, management, and family screening for affected individuals and their relatives.