60 Million Worldwide Carry Heart Disease Mutation

Jan. 24 -- FRIDAY, Jan. 23 (HealthDay News) -- About 60 million people worldwide carry a gene mutation that almost always causes heart disease, but the mutation is most common among people in India, according to a study by 25 researchers from four countries.

Heart disease is the leading cause of death in the world. By 2010, India will account for about 60 percent of the world's heart disease, said the researchers, who analyzed the DNA of about 800 patients at cardiac centers in India. The study was published in the Jan. 18 issue of Nature Genetics.

The mutation, a deletion of 25 letters of genetic code from the heart protein gene MYBPC3, was discovered five years ago in two Indian families with a history of cardiomyopathy, an enlargement or abnormal thickening of the heart muscle that weakens the heart and reduces its ability to pump blood.

The genetic risk of heart disease is expressed as an odds ratio. A small effect would be 1:2 and a large effect would be 2:0. The researchers said the odds ratio for people with the MYBPC3 mutation is almost off the scale, 7:0. People with the mutation usually have few symptoms until middle age. But after that, most develop symptoms and are at risk for sudden cardiac death.

"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," study leader Kumarasamy Thangaraj, Center for Cellular and Molecular Biology in Hyderabad, India, said in a news release issued by the Wellcome Trust Sanger Institute.

The researchers believe the mutation arose about 30,000 years ago in India, and spread because its effects usually develop only after people with the mutation have had children.

"The bad news is that many of these mutation carriers have no warning that they are in danger, but the good news is, that we now know the impact of this mutation," Perundurai S. Dhandapany, of Madurai Kamaraj University in Madurai, India, said in the news release.