We're all mutants, say scientists

September 3, 2009

By Sudeep Chand Science Reporter, BBC News

Each of us has at least 100 new mutations in our DNA, according to research

published in the journal Current Biology.

Scientists have been trying to get an accurate estimate of the mutation rate for

over 70 years.

However, only now has it been possible to get a reliable estimate, thanks to

" next generation " technology for genetic sequencing.

The findings may lead to new treatments and insights into our evolution.

In 1935, one of the founders of modern genetics, JBS Haldane, studied a group of

men with the blood disease haemophilia. He speculated that there would be about

150 new mutations in each of us.

Others have since looked at DNA in chimpanzees to try to produce general

estimates for humans.

However, next generation sequencing technology has enabled the scientists to

produce a far more direct and reliable estimate.

They looked at thousands of genes in the Y chromosomes of two Chinese men. They

knew the men were distantly related, having shared a common ancestor who was

born in 1805.

By looking at the number of differences between the two men, and the size of the

human genome, they were able to come up with an estimate of between 100 and 200

new mutations per person.

Impressively, it seems that Haldane was right all along.

Unimaginable

One of the scientists, Dr Yali Xue from the Wellcome Trust Sanger Institute in

Cambridgeshire, said: " The amount of data we generated would have been

unimaginable just a few years ago.

" And finding this tiny number of mutations was more difficult than finding an

ant's egg in an emperor's rice store. "

New mutations can occasionally lead to severe diseases like cancer. It is hoped

that the findings may lead to new ways to reduce mutations and provide insights

into human evolution.

ph Nadeau, from the Case Western Reserve University in the US, who was not

involved in this study said: " New mutations are the source of inherited

variation, some of which can lead to disease and dysfunction, and some of which

determine the nature and pace of evolutionary change.

" These are exciting times, " he added.

" We are finally obtaining good reliable estimates of genetic features that are

urgently needed to understand who we are genetically. "

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