Of mice and men: DNA similarities

Mice and men are genetically far further apart than was previously thought, calling into question the important role the rodents play in medical research.

A study has found while mice and humans share many protein-coding genes, the way their genes are regulated is often very different.

US scientists were surprised to find that gene activity diverged wildly between the two species in some key biological pathways.

The finding may help explain why more than 90% of new medicines that pass animal tests then fail in human trials. Laboratory mice have been a pillar of medical research for more than a century, being used by scientists investigating everything from social behaviour to obesity.

Professor Bing Ren, from the University of California at San Diego, who co-led the research, said: “The assumption has long been whatever was discovered in the mouse would likely be true in humans too, but the idea has never been systematically evaluated.

“We know now that this assumption is not entirely true. There are a substantial number of mouse genes that are regulated in ways different from similar genes in humans. The differences are not random. They are clustered along certain pathways, such as in genes regulating the immune system.”

The research is published in the journal Nature. It is part of the Encode (Encyclopedia of DNA Elements) project comparing functional parts of the human and mouse genome.