4 crore Indians carry `genetic` risk of cardiac arrest: study

Abhishek Shukla
New Delhi, Jan 18 (PTI) Every 25th Indian carries a
mutant gene which makes the person vulnerable to an "almost
guaranteed" risk of sudden cardiac arrest, results of a study
published Sunday suggest.

The mutated gene is carried by six crore people around
the globe of which more than four crores are Indians,
researchers said.

"...carries a mutation almost guaranteed to lead to heart
problems...," the study said, the findings of which were
published in latest edition of the journal 'Nature Genetics'.

"We can confidently say that four percent of the Indian
population is at risk of a sudden cardiac arrest as they carry
this mutant gene," Kumarasamy Thangaraj of Centre for Cellular
and Molecular Biology (CCMB), Hyderabad, who led the study,
told PTI.

The CCMB is a government lab functioning under the
Council of Scientific and Industrial Research (CSIR).

India has a burgeoning population of heart patients and
according to a previous study the country will constitute 60
per cent of global heart patient by 2010. The new findings
shed light on the genetic pre-disposition that increases risk
of heart disease in Indians.

People having this mutation have 25 letters of genetic
code deleted from a gene MYBPC3 -- responsible for production
of heart muscle protein. The altered form produces an abnormal
protein which disturbs the structure of heart muscle fibre.

"Those having the altered form of gene have seven folds
higher chances of getting a cardiac arrest than normal people.
Besides, these people have no warning about the danger which
makes it worse," Thangaraj said.

"Young people degrade the altered protein, hence they
don't generally show symptoms. But with age, the degradation
becomes less effective, making a mutant protein build up and
symptoms develop," said Chris Tyler-Smith, a researcher from
Wellcome Trust Sanger Institute, UK, in an e-mail interview.

"From our data, around 90 per cent of people carrying
this form of gene, who live to old age will develop symptoms
of heart disease," Chris said.

The mutation was discovered five years ago in two Indian
families but its significance became apparent only after the
study of about 1,500 people from different parts of country.

The study involving 25 scientists from four countries shows
that gene has slightly higher prevalence in south Indian than
in the north but affects all groups and religions, he added.

"We think that the mutation arose around 30,000 years ago
in India, and has been able to spread because its effects
usually develop only after people have had their children. A
case of chance genetic drift: simply terribly bad luck for the
carriers," said Perundurai S Dhandapany from Madurai Kamraj
University, one of the researchers.

"If this mutation is present in both copies of chromosomes
(one from father and another from mother), chances of getting
a heart attack are even higher than the person who has got the
mutant gene from only one of the parents," Thangaraj said.

Researchers are of the view that this finding will help
in identifying potential heart patients at young age by
genetic screening and adopt a healthier lifestyle to prevent
the further complications at advanced age. PTI