Biologists and medical doctors study two kinds of rearrangements: clinical and evolutionary. Clinical rearrangements are manifested as a rather common chromosomal abnormality, associated with such diseases as Down syndrome, cancer, and infertility. Many healthy individuals also carry an asymptomatic chromosomal rearrangement. Evolutionary genome rearrangements, on the other hand, have occurred only about once or twice every million years in the course of mammalian evolution. "While clinical rearrangements affect a single individual, evolutionary rearrangements affect all individuals in a particular species and lead to speciation, for example, to separation of human and mouse lineages," explained Pevzner. "The human and mouse genome sequences can be viewed as two decks of cards obtained by re-shuffling from a master deck--an ancestral mammalian genome."
Because the mouse carries virtually the same set of genes as the human but can be used in laboratory research, information about the mouse genome will allow scientists to test experimentally and learn more about the function of human genes, leading to better understanding of human disease and improved treatments and cures. Said Pevzner: "If clinical and evolutionary rearrangements are related (still an open question), then studying evolution could yield insights about cancer and infertility, and vice versa."
In the Nature paper, scientists comparing human and mouse genomes found that more than 90 percent of the mouse genome could be lined up with a region on the human genome. That is because the gene order in the two genomes is often preserved over large stretches, called 'conserved synteny.' In fact, the mouse genome could be parsed into some 350 segments, or chapters, for which there is a corresponding chapter in the human genome. For example, chromosome 3 of the mouse genome has chapters from human
Contact: Doug Ramsey
University of California - San Diego