New Research Reveals Heart Rhythm in Our Genes
Heart disease is the leading cause of death in the world. Over half of the nearly seven million deaths per year are caused by serious heart rhythm disturbances such as ventricular fibrillation.
Electrical signals originating in the heart’s pacemaker control the heartbeat. This electrical signal is transmitted by specialized proteins in heart muscle cells called ion channels. The researchers report the discovery of a new ion channel in the heart called SCN10A, which directly influences heart rhythm disturbances and a person’s risk of cardiac arrest caused by ventricular fibrillation.
The mutation identified in the SCN10A gene is common and, at an individual level, has a modest effect on a person’s risk of having heart rhythm problems. Further research is needed to determine what other mutations exist in this gene, and whether these variants might have a stronger effect.
After analyzing the genetic make-up and electrocardiograms (ECG) of almost 20,000 people, the researchers discovered that a variation in the gene that encodes the ion channel SCN10A was associated with slow and irregular heart rhythms, including risk of ventricular fibrillation.
The researchers then identified the protein in human and mouse heart muscle cells. The scientists then tested their findings by comparing the heart rhythm of mice with and without the SCN10A gene. The results showed that mice without a functioning SCN10A gene had shortened heartbeats, providing confirmation that the gene regulates heart rhythm.
Dr John Chambers, lead author of the study from the Division of Epidemiology, Public Health and Primary Care at Imperial College London, said: “Genetic variation is like the two sides of a coin. One side is associated with increased risk, the other with decreased risk. We have identified a gene that influences heart rhythm, and people with different variants of the gene will have increased or decreased risks of developing heart rhythm problems.
“Though the gene variant itself may only have a small effect on a person’s risk of having heart rhythm problems, our study gives us important new insight into the mechanisms affecting disordered heart rhythm,” added Dr Chambers.
Professor Jaspal S Kooner, corresponding author of the study from the Division of Epidemiology, Public Health and Primary Care at Imperial College London, said: “These results may enable us to predict and diagnose serious heart rhythm disturbances better, and in the future develop improved treatments for preventing ventricular fibrillation, which is a leading cause of death worldwide.”
Professor Douglas Kell, BBSRC Chief Executive, said: "Having an understanding of the genetics behind a healthy heart gives us access to appreciating what has gone wrong when a person's cardiovascular health suffers. This research gives us part of a very complicated picture of how the heart works on a molecular level."
“Genetic variation in SCN10A influences cardiac conduction and risk of ventricular fibrillation” Nature Genetics, Sunday 10 January 2010; John C. Chambers, Jaspal S. Kooner, et al