A new study, published in `The Lancet` journal, has revealed that the same gene which creates the enzyme that causes people to be blood group `O` gives them some protection against heart attacks.
The study was carried out by an international team led by researchers from Cardiovascular Institute at Pennsylvania University in the US.
For their study, the researchers compared almost 6,000 people who had suffered a heart attack with 7,400 people who had a type of coronary heart disease, but had not had a heart attack, `The Daily Telegraph` reported.
They described the association as "notable, in view of decades of work suggesting a relation between ABO blood-groups and both thrombosis and coronary heart disease".
However, the study did not look to quantify how much extra protection being blood group `O` might give someone from having a heart attack.