FOR RELEASE: 5:00 P.M. Eastern, July 29, 1996
CONTACT: NHLBI Information Office, (301) 496-4236
SCIENTISTS FIND FIRST EVIDENCE OF GENES DIRECTLY CONNECTED TO STROKE
A research team supported by the National Heart, Lung, and Blood Institute (NHLBI) has found the first direct evidence for the existence of genes connected to stroke.
Scientists at Brigham and Women's Hospital in Boston have identifed the approximate location of three stroke-related genes in a particular strain of hypertensive rats that provides a strong model for human stroke. Two of the genetic factors protected the rats against stroke and the third predisposed the rats to stroke. The study appears in the August issue of Nature Genetics.
"For the first time, we have direct evidence for the location of genes that specifically contribute to stroke," said Dr. Claude Lenfant, NHLBI director. "This study is a critical first step in isolating the genes," he said.
For years, scientists have suspected that there are direct genetic components to stroke. This was thought to partially explain why some people with hypertension get strokes and others do not. The challenge has been to distinguish the specific genetic factors involved with stroke from those genetic factors responsible for hypertension, a major risk factor for stroke.
The research team accomplished this by studying the second generation offspring derived from mating two different strains of hypertensive rats. One strain of rats developed stroke if given a high sodium, low potassium diet. The other strain was resistant to stroke despite the underlying hypertension and special diet. Since all of the second generation rats had hypertension, the scientists were able to tease out the influence of stroke-specific genetic factors.
The age of onset of stroke (after they were placed on the special diet) was the main parameter used by Dr. Klaus Lindpaintner and his colleagues to assess the rats' genetic susceptibility to stroke. Genome screens on this second generation of rats revealed that a locus (location) on chromosome 1 showed a "highly significant linkage to the occurrence of stroke." The rats with this genetic makeup had early strokes. In addition, Lindpaintner reported that loci on chromosomes 4 and 5 offered a modest protective effect against stroke.
"This study reinforces the complex nature of stroke. This disease--which is the third leading cause of death in the U.S. is influenced by several genes in addition to well-recognized risk factors such as hypertension, diet, and smoking," said Dr. Lenfant.
Dr. Lindpaintner noted that the stroke seen in the rat model studied "almost strikingly resembles human stroke."
"If we can identify the genes contributing to stroke," added Dr. Lindpaintner, "it's our hope that we can learn more about the mechanism of this disease so as to ultimately develop custom-designed treatment."
To arrange an interview with NHBLI program officer Dr. Stephen Goldman, phone the NHLBI Press Office at 301-496-4236. To interview Dr. Lindpaintner, contact the Press Office at Brigham and Women's Hospital at 617-732-5211.