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Global research team finds that mutant gene common in South Asians increases risk of cardiomyopathy
HYDERABAD, India—One percent of the world's population is likely at much greater risk of heart failure thanks to a particular mutant gene that increases the risk of cardiomyopathy in South Asians, according to researchers from India, the United Kingdom and the United States.
The scientists' findings, published in the article A common MYBPC3 (cardiac myosin binding protein C) variant associated with cardiomyopathies in South Asia in the peer-reviewed journal Nature Genetics in January, say that 4 percent of people of South Asian descent carry this MYBPC3 mutation, which increases their risk of developing cardiomyopathy by seven times compared to the general population.
"The mutation leads to the formation of an abnormal protein," says one of the researchers, Kumarasamy Thangaraj of the Centre for Cellular and Molecular Biology in Hyderabad. "Young people can degrade the abnormal protein and remain healthy, but as they get older it builds up and eventually results in the symptoms that we see."
To come to this finding, the global team first compared 800 heart patients in India with 699 others without the condition, discovering that the genetic mutation was much more common among the heart patients.
In fact, the researchers wrote that the link between the symptoms and the genetic defect "were almost off the scale."
Next, they looked at 28 unrelated families carrying the mutation in different parts of India and found that more than 90 percent of the oldest members in each family had heart problems.
After that, the researchers screened 6,273 randomly-selected individuals across 35 states in India and discovered that 4 percent had the mutation, though most of the mutations were found in the southern and western portions of the country.
Finally, they tested 2,085 people from 26 countries and found that the condition appeared to be restricted only to people of South Asian descent whose origins are in India, Pakistan, Sri Lanka, Indonesia and Malaysia.
It is rare, noted the study's researchers, to find a gene that has such a large effect and is also so common.
This may help explain why South Asia accounts for a disproportionately large share of the world's cardiovascular disease cases. Around 30 percent of global deaths each year are due to heart disease and other cardiovascular problems, and the World Health Organization estimates that by 2010, India alone will account 60 percent of the world's heart patients.
It is unclear, however, is how much this discovery will help in the near term. Certainly, one route of commercialization that could come out of this research would be screening tests that could identify carriers of the gene in the womb or at an relatively young age.
But as noted by Chris Tyler-Smith, a senior investigator at the Wellcome Trust Sanger Institute in the United Kingdom and one of the study's researchers, healthcare professionals would only be able to offer to such people the same advice they offer generally to people to avoid heart disease: have a healthy diet, exercise and avoid smoking. In its own commentary about the study, Britain's National Health Service came to the same conclusion, and also noted that while the study assessed the increase in risk of cardiomyopathy with this mutation, it did not address whether that necessarily meant an increase in the risk of actual heart failure.
Also, as Peter Weissberg, medical director at the British Heart Foundation, notes, "There is no evidence yet that early detection will lead to improved outcome since we have no idea if the outlook for this group can be modified by conventional heart failure treatments."
But Tyler-Smith sees commercial opportunities in the future for therapies as more understanding of the mutation and its effect come to light.
"In the longer term I think trying to improve the efficiency of the protein degradation mechanism might be a novel approach for treatment," he says. "All you would have to do is postpone the effects for a few decades." DDN