Posted by Marilyn on December 13, 2002 at 07:13:00:
Dec. 12, 2002
Israeli-developed gene test for diabetics can target high risk for heart disease
By JUDY SIEGEL-ITZKOVICH
A one-time cheap, simple blood test can pick out which diabetics carrying a specific form of gene are at 500% higher risk for developing cardiovascular disease than those who bear another form of the gene.
The connection between gene types in diabetics and heart disease was discovered and the blood test developed by Technion researcher Dr. Andrew P. Levy.
The assay, which he said should become available in Western countries in a year, looks for a gene on chromosome #16 that Levy and his colleagues found in diabetics with a much higher risk of heart disease. He said the predictive gene test could "revolutionize" preventive treatment of the 70% of type I and type II diabetics who will at some time in the future develop cardiovascular problems.
"By accurately determining which people with diabetes are at greatest risk for heart disease with a genetic test, there is no telling how many lives we could save with early intervention techniques," Levy told The Jerusalem Post on Wednesday.
The Israeli team, which published their findings in the December 4 issue of The Journal of the American College of Cardiology, said they could identify diabetics at risk for heart disease at any age, before they developed cardiovascular symptoms. Their doctors could then focus on aggressive measures for getting them to quit smoking, reducing their blood cholesterol levels, lowering blood pressure, and minimizing other risk factors to head off their getting heart disease.
Levy, who was born in the Washington, D.C. area and studied medicine in Boston, came on aliya from Washington five years ago, going directly to a job at the Technion. His team examined the genetic makeup of individuals in a sample from the Strong Heart Study, a population-based longitudinal study of heart disease in Native Americans (Indians), a group previously thought to be resistant to developing heart disease but who are now showing a very high rate of diabetes and heart disease. To conduct the study, they obtained blood samples from this group and examined their genetic makeup in Israel.
The relative genetic homogeneity of this population, along with the high prevalence of diabetes, made it an ideal group to study, Levy said. The sample group included 206 heart disease patients and a control group of 206 people, all aged between 45 and 74. Using stored blood samples, the researchers looked at haptoglobin, a blood protein found in three different forms: 2-2, 1-1 and 2-1. Individuals with the 2-2 form were five times more likely to have heart disease than those with the safer 1-1 form. An intermediate risk was associated with those with the 2-1 form.
Prof. Chaim Lotan, head of cardiology at Hadassah-University Hospitals, said he and colleagues plan to conduct studies using the test to determine exactly how common the gene is among Israeli diabetics and assess its influence on heart disease. "This is a polymorphic gene; it comes in several forms and was apparently created some 100,000 years ago. It isn't certain why one form is more risky for heart disease among diabetics, but it may have something to do with heavy metals in the body. The gene can't tell doctors if a patient will get diabetes, but among diabetics it can pick out those who are much more likelihood of getting heart disease," said Lotan.
"Knowing this won't cure heart disease, but it can prevent serious complications by getting them to change their diet and lifestyle and taking medications at an early age."
Lotan added that it's "premature to immediately begin testing on Israeli diabetics. We have to do more studies to test various ethnic groups, and we plan to do it at Hadassah. Before you do full screening, you have to know more about correlation and other data."
Levy said he tried to interest Clalit Health Services in the test but "got the runaround." But when Maccabi Health Services director-general Prof. Yehoshua Shemer heard from the Post about the test, he said: "Anything that prevents disease is good, and prevention is cost effective compared to treating disease, but I have to study this new technology before we decide whether to use it." "This is an entirely novel and new idea that will certainly attract attention from many clinical investigators and scientists worldwide," said Dr. Myron Weisfeldt, head of the department of internal medicine at The Johns Hopkins Medical Institutions in Baltimore.
Levy's team reported that about half of the Native Americans who carried the gene had 2-2 form and the other half bore the 2-1 form; subsequent studies on some Israelis have shown that 30% of those who carried the gene had the 2-2 type and 70% had the 2-1 type. The two types are not found naturally in mice or any other animals, even primates, so an animal model could not be used in developing the test.
Seven out of 10 diabetics eventually develop heart disease, which is its most common, expensive and severe complication. The risk of cardiovascular disease among diabetics is not uniform, as geographic and ethnic differences also affect it.
Unlike other recent discoveries such as the test for C-reactive protein, the patented Technion test does not have to performed periodically. Since it is a test and not a treatment, approval by the US Food and Drug Administration and other licensing agencies around the world should "not take long," Levy said.
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