Heart disease gene affects one in 100, say scientists

Mutation all but guarantees serious illness in middle age for 60m people worldwide

A gene that almost guarantees serious heart disease in middle age is carried by an estimated 60 million people around the world, a team of scientists has found.

The one in 100 who inherit the mutation usually show few, if any, symptoms before their 40s, but become ill as they get older, with many later dying from heart failure.

The discovery marks the strongest link yet that scientists have made between a person's genetic make-up and their risk of succumbing to heart disease.

The risk of being born with the abnormal gene is substantially higher in people who can trace their ancestry back to the Indian subcontinent, where one in 25 inherit the mutation. "The bad news is that many of these mutation carriers have no warning that they are in danger," said Perundurai Dhandapany at Madurai Kamaraj University, a co-author of the study published in Nature Genetics.

The mutation was originally identified in two Indian families with heart disease five years ago, but only after studying almost 1,500 people from different regions of India did the importance of the abnormal gene become clear.

Researchers compared the genetic make-up of 800 patients with heart disease and 699 healthy volunteers. They found those with heart problems often carried the mutation, in which 25 letters of genetic code needed to make heart muscle proteins are missing.

"The mutation leads to the formation of an abnormal protein. Young people can degrade the abnormal protein and remain healthy, but as they get older it builds up and eventually results in the symptoms we see," said Kumarasamy Thangaraj at the Centre for Cellular and Molecular Biology in Hyderabad, who led the study.

Chris Tyler-Smith, a co-author at the Sanger Institute near Cambridge, said the mutation probably arose in India around 30,000 years ago and was able to spread because it usually only affects people after they have had children.

With genetic screening it would be possible to identify people with the gene at an early age, though in the near term, doctors could only advise them to improve their lifestyle to reduce their risk of heart disease. In the longer term, scientists hope to develop a treatment using a drug to boost the body's ability to break down the abnormal heart protein.
