Mouse genetic code unveiled

The first complete draft of the entire mouse genome was published in Nature last week, accompanied by studies presenting an analysis of mice genes, and a comparison with their human equivalents. The scientists found that, like humans, mice have around 30,000 different genes, and that only about 300 are unique to each species.

This similarity means that the mouse genome will be invaluable to researchers studying genes involved in human diseases. 'We have deciphered the mouse book of life, and translated this huge tome into a meaningful edition for the research community' said Jane Rogers, head of sequencing at the Wellcome Trust Sanger Institute in Cambridge. An international consortium of scientists carried out the project, funded by a mixture of government, charity and commercial organisations.

The studies also revealed that vast tracts of the human genome that do not form part of genes - often referred to as junk DNA - have remained largely unchanged since mice and people went their separate evolutionary ways. This surprising finding suggests that much of the 'non-coding' DNA is actually just as important as the 'coding' DNA that makes up genes. It is thought that much of it will turn out to consist of genetic switches, controlling how, when and where genes are switched on and off in the body.

Eric Lander, director of genome research at the Whitehead Institute for Biomedical Research in Cambridge, US, commented that 'there's a lot more that matters in the human genome than we had realised'. He added that knowing what all the players were would make a huge difference in being able to understand the basis of disease.

Mice and people last shared a common mammal ancestor around 75 million years ago, and most mouse genes still have an equivalent human gene. But the researchers found some notable differences - mice have additional, unique genes involved in smell, reproduction, breaking down toxins and immunity. The scientists reported 9000 previously unidentified mouse genes, and discovered the role of 1200 human genes, following a comparison of the mouse and human genomes. Professor Robert Winston, director of NHS research and development at Imperial College, London, said the landmark announcement 'will undoubtedly further our understanding of the molecular basis of human diseases and the treatment of the widest range of human disorders'.