Scientists have discovered a chromosomal clue that may point to a person’s risk of developing heart disease.

The key is in the length of the telomeres — stretches of DNA on the ends of chromosomes, like caps on shoelaces.

The telomeres of babies are long. Every time a cell divides the telomeres get shorter, acting as a marker of age, but they do not shorten at the same rate for everyone.

A team led by Nilesh Samani of the University of Leicester studied the telomeres in the white blood cells of more than 1,500 men. They found that the 484 men who went on to develop coronary heart disease had shorter telomeres than the 1,058 who did not.

Previous research had shown that people with heart disease were likely to have shorter telomeres. But it was not clear whether this was a consequence of heart disease or a herald of it. The findings, published in The Lancet, indicate that short telomeres may be an early indiction of heart problems to come.