The international Mouse Genome Sequencing Consortium sequenced and analyzed more than 95 percent of the genetic code of Mus musculus, which contains about 2.5 billion DNA base pairs compared to 2.9 billion in the human genome. "We share 99 percent of our genes with mice," says Jane Rogers of the Wellcome Trust Sanger Institute in Cambridge, England, "and we even have the genes that could make a tail." In fact, only about 300 genes are unique to either organism, which further supports the use of the mouse models for studying various diseases as well as testing novel treatments. The key differences lie in those areas of the genome governing immunity, detoxification, smell and sex, which makes sense considering where rodents usually live, how they find food and the number of offspring they can produce.
According to Allan Bradley, also at the Wellcome Trust Sanger Institute, the mouse genome "is a huge asset to researchers, and its significance matches that of the human genome." Indeed, by comparing specific sections of the mouse genome to our own, scientists can garner insight not evident from examination of our genetic code alone. For example, additional findings published today in Nature by Stylianos Antonaradkis of the University of Geneva Medical School and his colleagues highlight the similarity of non-protein-encoding sequences between man and mouse. By comparing human chromosome 21 to the corresponding section of the mouse genome, the team determined that 2,262 nongene DNA segments have been conserved. Because evolution has left these chunks of DNA intact, the scientists posit that they play an important role and could exert control over other genes at specific times and places, or provide chromosomes with the necessary structure to function properly.