In a major breakthrough of medical science, a team of scientists led by Indians has identified a defective gene responsible for the sudden cardiac arrest and deaths among the population in the Indian sub-continent.

The study piloted by the Hyderabad-based Centre for Cellular and Molecular Biology (CCMB) and involving scientists from India, Pakistan, the US and Britain has given hope to 60 million people carrying the defective gene by way of stem cell therapy or a possible drug.

Announcing the results of the five-year long study, CCMB director Lalji Singh told reporters here Monday that it was the defect in one gene Myosin binding protein-C (MYBPC3), which regulates pumping of blood, accounting for 45 percent sudden cardiac arrests or sudden death due to heart problems.

'We found this particular gene in certain individuals with 25 base pairs missing and it makes defective protein,' he said.

'This, however, does not represent all the problems of heart. Two to five percent of heart problems are due to sudden heart attack and this represents 45 percent of that two to five percent,' said Singh, who was one of the eminent scientists who participated in the study.

The study was conducted by an international team of 25 researchers led by the CCMB scientists. The results of the research were published in the prestigious scientific journal 'Nature Genetics' in the US.

Significantly the researchers found that general defect was found only in the people of Indian sub-continent, including countries like India, Pakistan, Sri Lanka, Indonesia and Malaysia but not in other countries.

'Bangladesh was not covered by the study but since it has the same origin, we believe that the defective gene is also found in that country,' said the CCMB director.

The scientists analysed the DNA of 800 cardiac patients from Hyderabad, Madurai, Thirunalveli, Thiruvananthapuram, Kozhikode, Mumbai, and Bhubaneswar, Delhi and Chandigarh and 699 normal individuals from the ethnically matching groups.

The scientists also screened 6,273 randomly selected individuals to find out how widespread the mutation was in the Indian population. These cases were from 107 ethnic populations including primitive tribes, tribes, castes, subcastes and people belonging to all the religious groups including Hindus, Sikhs, Muslims and Christians from across the country.

'If there is only one defective gene in an individual, he may live up to the age of 40 to 45 and then suddenly die because of heart attack without showing any symptoms before. We can identify such individuals in familiar cases (where there are families where people die because of sudden heart attacks).'

'Any gene occurs in pairs, one coming from father and one coming from mother. If both genes are defective, you call it homozygous.'

He said such people could be identified much before they are born through pre-natal diagnosis.

'Taking the sample of mother's blood, we can tell if the one gene of the baby is defective or both. If both genes are defective we can advise parents to have abortion. If one gene is defective, the doctors can advise the patient to live stress-free life to live longer.'

He said the study had thrown an opportunity for pharmacological companies to develop a drug which can degrade one of the defective proteins.

'There is a machinery in the cell which degrades abnormal protein. As you become older beyond the age of 40, the machinery becomes weaker and the cell starts accumulating both defective protein as well as normal protein.'

Lalji Singh said such individuals might get some treatment through stem cell therapy in future.

K. Thangaraj, a CCMB scientist, said it was estimated that about 60 million people in the region were carrying this mutant gene. About 30 million people in India suffer from heart disease, and by 2010 India will carry 60 percent of the burden of world's heart diseases.