Thursday, September 3, 2009
All humans have at least 100 new mutations in their DNA
Scientists have been trying to get an accurate estimate of the mutation rate for over 70 years. In 1935, one of the founders of modern genetics, JBS Haldane, studied a group of men with the blood disease hemophilia. He speculated that there would be about 150 new mutations in each human. 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.