The gene controls electric signals

A study of four generations of a Chinese family has pinpointed a faulty gene that helps control the heart's electrical activity.

The discovery should lead to better diagnosis and treatment of atrial fibrillation, which affects about 3% of the population.

It is the commonest cause of the heart beating irregularly, particularly in the elderly.

The heart disorder is due to a problem with the electrical signalling of the heart.

When electrical impulses travel along pathways to the heart muscle they trigger the muscle to contract, keeping the heart beating regularly.

If something damages or interferes with the transmission of these electrical impulses then the heart may beat faster and irregularly. This can eventually lead to heart failure and other problems.

Novel approach

A research team in China and France has traced the problem to a gene found on chromosome 11, one of the 24 distinct bundles of chromosomes in the human body.

It codes for a channel that controls the flow of charged potassium ions in and out of certain heart cells.

The gene, known as KCNQ1, is unlikely to be the whole story, as some patients with the disorder do not have the mutation. However, it should speed the search for new treatments.

"Our results may suggest new therapeutic strategies for both the inherited and the more commonly acquired forms of atrial fibrillation," say the team leaders Yi-Han Chen of Tongji University, Shanghai and Shi-Jie Xu of the Chinese National Human Genome Centre.

UK charity, the British Heart Foundation, said the research was interesting despite the small sample size.

"We would welcome larger and more in-depth studies to help us understand this condition, which is estimated to affect around 5% of people over 70 and sometimes younger people too," said cardiac nurse Alison Drugan.

The study is published in the journal Science.