A person with a problem may appear to be in good health, but they are vulnerable to risky cardiac electrical activity patterns that could result in palpitations, blackouts, or even death.
A study of 1,029 genomes revealed that one in 100 apparently healthy Indians carries genetic abnormalities associated to heart electrical problems that might cause sudden cardiac death. The researchers have published their findings in the peer-reviewed journal Human Genomics.
The study emphasises the significance of genetic tests to identify high-risk people who have no outward signs of illness. It is the first of its kind in India to determine through genomes the population incidence of illnesses called cardiac ion channelopathies.
19 (1.8%) of the 1,029 whole genomes derived from healthy volunteers were discovered to include genetic variants associated with channelopathies by a group of genomics researchers and medical professionals. Ten of these 19, or 0.97 percent of the 1,029 volunteers overall, exhibited genetic changes that are unquestionably responsible for these illnesses.
Even though they may otherwise appear healthy, people with these diseases are vulnerable to risky patterns of cardiac electrical activity that can result in palpitations, blackouts, or even sudden death. These patterns are frequently brought on by physical exertion or mental stress.
“It’s a bit like the sword of Damocles,” said Sridhar Sivasubbu, a scientist at the Institute of Genomics and Integrative Biology, New Delhi, who led the study. “But in the majority of cases, the risk of such consequences may be minimised by medicines or devices such as cardiac pacemakers.”Given India’s large population, even a conservative 1 per cent prevalence of these variations would pose a large health burden for the country, Sivasubbu and his collaborators at the IGIB and the All India Institute of Medical Sciences, New Delhi, said.
A diagnostic test for such screening is now being developed by researchers at the IGIB. Numerous studies have attempted to calculate the frequency of sudden cardiac death in India, however cardiologists claim that the proportion of deaths from channelopathies is still unknown because sudden death can also result from undetected coronary artery disease.
“People who have a family history of sudden cardiac death, or who have experienced blackouts or palpitations without apparent cause could be possible candidates for (genetic) screening,” said Anjali Bajaj, the first author of the study.
A 2012 study in Andhra Pradesh extrapolated 700,000 sudden cardiac deaths in India each year using a sample of 1,691 deaths. Worldwide research teams have discovered 36 genes whose variations are linked to cardiac ion channelopathies over the past 20 years. In order to investigate potential links between genes and health, the IGIB-AIIMS team examined the complete genomes of 1,029 healthy people who provided blood or saliva samples.
Their investigation of the dataset found 470 genetic variations involving the 36 genes, 124 (26%) of which were specific to the Indian population. In 19 of the 1,029 volunteers, 13 variations associated to channelopathies were discovered, and 10 mutations known to unmistakably cause the illnesses were discovered in 10 volunteers.
Given that India’s population is made up of over 4,000 ethnic groupings as a result of numerous inward migrations and admixtures over centuries, scientists say the existence of the rare variances is not surprising.
Parvathy Sukumaran 
