We're all mutants, say scientists

By Sudeep Chand Science Reporter, BBC News

Each of us has between 100 and 200 new genetic mutations

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 letters of the genetic code within 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.

Joseph 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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