Short QT Syndrome
Return to Library
What is short QT syndrome?
Short QT syndrome is a condition that causes a disruption of the heart's normal rhythm (arrhythmia). In people with this condition, the heart (cardiac) muscle takes less time than usual to recharge between beats. If untreated, the irregular heartbeats can lead to a spectrum of signs and symptoms, from dizziness and fainting (syncope) to cardiac arrest and sudden death.
The signs and symptoms of short QT syndrome, including sudden death, can occur any time from early infancy to old age. This condition may explain some cases of sudden infant death syndrome (SIDS), which is a major cause of unexplained death in babies younger than one year. Other people with short QT syndrome never experience any health problems associated with the condition.
How common is short QT syndrome?
Fewer than 30 cases of short QT syndrome have been identified since this condition was discovered in 2000.
What genes are related to short QT syndrome?
Mutations in the KCNH2, KCNJ2, and KCNQ1 genes cause short QT syndrome.
The KCNH2, KCNJ2, and KCNQ1 genes provide instructions for making proteins that act as channels across the cell membrane. These channels transport positively charged atoms (ions) of potassium into and out of cells. In cardiac muscle, these ion channels play critical roles in maintaining the heart's normal rhythm. Mutations in the KCNH2, KCNJ2, or KCNQ1 gene increase the activity of the channels, which changes the flow of potassium ions between cells. This disruption in ion transport alters the way the heart beats, leading to the abnormal heart rhythm characteristic of short QT syndrome.
How do people inherit short QT syndrome?
Short QT syndrome appears to have an autosomal dominant pattern of inheritance, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Some affected individuals have a family history of heart problems and sudden cardiac death. Other cases are classified as sporadic and occur in people with no apparent history of short QT syndrome in their family.
Source: National Institutes of Health
|
Free Short QT Syndrome Articles |
|
|
|
|
Researchers from University of Bristol describe findings in arrhythmia
2009 JUN 8 - (NewsRx.com) -- According to recent research from Bristol, the United Kingdom, "The short QT syndrome (SQTS) is a cardiac repolarisation disorder characterised by abbreviated (IT intervals on the electrocardiogram and by an increased risk of atrial and ventricular arrhythmias and sudden death. The SQT1 variant involves a gain-of-function mutation (N588K) that impairs inactivation of the hERG (human ether-a-go-go-related gene) potassium channel and, thereby, increases current mediated by the rapid delayed rectifier potassium current 0 K,) in the heart." "Here, the action potential voltage clamp (AP clamp) technique was applied to Chinese Hamster Ovary cells expressing wild-type or N588K-hERG at 37 degrees C, to compare effects of the N588K mutation oil hERG current (I-hERG) during ventricular, atrial and Purkinje fibre APs. The N588K mutation altered the IhERG profile during each AP type; increased maximal repolarising current occurred earlier during AP repolarisation (with shifts of similar to+60 mV, +30 mV and +15 mV respectively for ventricular, Purkinje fibre and atrial APs). Thus SQT1 may influence repolarising IhERG for each cell type, with AP clamp experiments and simulation data indicating the greatest effect during ventricular APs," wrote M.J. Mcpate and colleagues, University of Bristol. The researchers concluded: "Changes in the timing of outward I-hERG transients elicited by premature stimuli following AP commands indicate that SQT1 may alter the protection that hERG provides cardiac tissue against premature arrhythmogenic stimuli." Mcpate and colleagues published their study in the Journal of Physiology and Pharmacology (COMPARATIVE EFFECTS OF THE SHORT QT N588K MUTATION AT 37 degrees C ON HERG K+ CHANNEL CURRENT DURING VENTRICULAR, PURKINJE FIBRE AND ATRIAL ACTION POTENTIALS: AN ACTION POTENTIAL CLAMP STUDY. Journal of Physiology and Pharmacology, 2009;60(1):23-41). For additional information, contact J.C. Hancox, University of Bristol, School of Medicine Science, Bristol Heart Institute, Dept. of Physiol & Pharmacology, Bristol BS8 1TD, Avon, UK. Publisher contact information for the Journal of Physiology and Pharmacology is: Polish Physiological Society, Jagiellonian University School Med, Institute Physiology, 31-531 Krakow, 16 Grzegorzecka, Poland. Keywords: United Kingdom, Bristol, Arrhythmia, Cardiology, Drugs, Pharmaceuticals, Pharmacology, Physiology, Sudden Death, Therapies, University of Bristol. This article was prepared by Biotech Business Week editors from staff and other reports. Copyright 2009, Biotech Business Week via NewsRx.com.
|
