Every year, heart disease claims an estimated 7 million lives, according to the World Health Organization. Scientists have struggled to pinpoint the precise genes behind this complex disease. Now, however, they have a new research ally: the designer rat.
In a four-year study published in the January 15 advance online publication of Nature Genetics, researchers at The Institute for Genomic Research (TIGR) and the Medical College of Wisconsin (MCW) systematically bred and studied 43 designer rats with and without high blood pressure, in order to pinpoint candidate genes behind heart disease. In total, the scientists built 2,200 microarray gene expression profiles from these designer rats--providing a valuable new online resource now available to researchers worldwide.
Scientists have long used rat models to study heart disease in the lab. But those studies have yet to answer key questions: Which genes, on which chromosomes, combine to cause this complex condition? Why, and how, do some animals become hypertensive when consuming high-salt diets, while others stay healthy? To turn the tools of genomics onto these questions, the National Heart, Lung, and Blood Institute, part of the National Institutes of Health, funded the new study.
In the first part of the study, MCW researchers began with a strain of rats bearing high blood pressure, a hallmark of heart disease. The researchers then bred an almost identical designer rat, with one important change: they substituted one chromosome from the parental, hypertensive rat with the homologous chromosome from a healthy rat. Continuing this way, the team generated 22 unique designer rat strains, each bearing one distinct healthy chromosome substitution. Some of these new designer rats were disease-free, implying that their replaced chromosomes carried genes for high blood pressure and related conditions.