Each bit of DNA offers insights to better treatments, scientists say
SUNDAY, May 10 (HealthDay News) -- Two major international studies have identified what researchers describe as a treasure trove of genes linked to high blood pressure.
"In one fell swoop, to find so many genes related to blood pressure is one great opportunity," said the lead author of one of the studies, Dr. Christopher Newton-Cheh, an assistant professor of medicine at Harvard Medical School. His team analyzed genetic data from 130,000 individuals collected at 93 centers across the United States and Europe.
"These findings advance the biology of blood pressure regulation," added Dr. Daniel Levy, director of the U.S. National Heart, Lung, and Blood Institute. He led a second study that gathered genetic data on 29,000 people in the United States and elsewhere. The new findings "could lead to better predictions of who is likely to develop hypertension," he said.
The studies appear simultaneously in the May 10 issue of Nature Genetics and at the American Society on Hypertension annual meeting, in San Francisco.
Hypertension -- high blood pressure -- is a leading risk factor for cardiovascular problems such as heart attack and stroke. The ultimate hope is that the research effort will lead to new treatments aimed at specific genes, Newton-Cheh said.
"It is still very difficult to treat high blood pressure and new leads for new genes that we can target are sorely needed," he said.
In both studies, the researchers looked at variations in the sequences of DNA molecules that make up the human genome. They focused on what are formally called single-nucleotide polymorphisms (SNPs) associated with blood pressure differences.
In all, 13 gene regions not previously associated with blood pressure were identified in the two studies, Newton-Cheh said. "Several of their gene regions overlap with ours," he said. "Five were unique to one study, five were unique to the other and three gene regions were found in both."
Identifying those regions is just a first step toward better prevention and treatment of high blood pressure, Newton-Cheh and Levy said.
One reason is that each of the regions may individually exert only a small effect on blood pressure, Levy said: "Each of the risk variants changes systolic blood pressure by 1 millimeter and diastolic pressure by one-half millimeter," he said. Systolic blood pressure is the higher number in a blood pressure reading, diastolic the lower number.
"But it is possible that there are genes that have a profound effect on blood pressure in these regions," Levy said. "Digging more deeply could identify variants in these genes that have larger effects on blood pressure."
Answers may come from research with animal models of high blood pressure, he said. "One can do work with animals that can't be done with humans," Levy said.
Human trials can also help, Newton-Cheh said. "I am planning studies of people to understand which genes affect blood pressure and how," he said. "My group, among others, will try to identify a small number of people who have strong mutations. Those people are of great interest."
The hope is that drug companies will be drawn into the genetic research effort by the lure of profits from more effective blood pressure treatments, Newton-Cheh said. "They have lots of things on their shelves, and this offers potential leads for testing compounds that could lead to drugs," he said.
While research goes on, it is too early to recommend genetic screening for high blood pressure, Newton-Cheh said. "From the data we have now, there is no way we could advocate that people be tested," he said. "It will require some work to prove how genes affect blood pressure."
The basics of high blood pressure are explained at the U.S. National Library of Medicine.
SOURCES: Christopher Newton-Cheh, M.D., assistant professor, medicine, Harvard Medical School, Boston; Daniel Levy, M.D., director, Framingham Heart Study, U.S. National Heart, Lung, and Blood Institute, Bethesda, Md.; May 10, 2009, Nature Genetics, May 10, 2009, presentations, American Society on Hypertension annual meeting, San Francisco
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