Heart rhythm gene revealed in new research
11 January 2010
Heart disease is the leading cause of death in the world, accounting for almost seven million deaths per year. Over half of these deaths are sudden and caused by serious heart rhythm disturbances such as ventricular fibrillation. The gene identified in this new study is linked to these heart rhythm disturbances and reveals a new mechanism that controls the heartbeat.
A person's heartbeat is controlled by electrical signals, which start in one central place - the heart's 'pacemaker' - and travel around the heart muscle. This electrical signal is transmitted by specialised proteins in heart muscle cells called ion channels.
Researchers at Imperial College London, writing in 'Nature Genetics', have reported 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 new research, funded by the Wellcome Trust, BBSRC and the British Heart Foundation, shows that a common mutation in the SCN10A gene encoding this protein has a modest effect on a person's risk of having problems with their heartbeat. Further research is needed to determine what other mutations exist in this gene, and whether these variants might have a stronger effect.
The authors of the study hope their findings will enable scientists to develop new ways to prevent and treat heart rhythm disturbances.
Dr John Chambers, lead author of the study, 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."
Professor Jaspal S Kooner, corresponding author, 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."
In today's study, the researchers analysed the genetic make-up of almost 20 000 people to look for genetic factors influencing the heartbeat. They studied the electrocardiogram (a recording of the heartbeat) of each person, and measured the time taken for electrical signals to travel to different parts of the heart. The researchers discovered that 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. Although scientists had previously discovered the protein in nerve cells, this is the first time it has been identified in heart muscle cells.
The scientists 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.
Image: Mouse heart. Credit: Wellcome Images
Reference
Chambers, JC et al. Genetic variation in SCN10A influences cardiac conduction. Nat Genet [Epub ahead of print]
