Finding Gene That Causes Heart Disease

8:36 AM, Sep 11, 2012   |    comments
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Indianapolis, IN (written by Shari Rudavsky/Indianapolis Star) -- Doctors know that much of heart disease runs in families. Still, not everyone in a family inherits it. Until recently, identifying the problem gene was costly, time-consuming and in many cases near-impossible.

Improved technology, however, has opened the door for more affordable cardiac genetic testing.

Heart conditions lend themselves well to genetic testing. Most of the genes involved are dominant, meaning if a person inherits the gene from one parent, he or she will almost definitely develop the disease, says Dr. Glenn Bingle, a medical geneticist with the cardiovascular genetic counseling center at the Indiana Heart Hospital.

"As soon as you identify the change, you have struck the golden bullet. You can figure out where it is and isn't," Bingle said. "It's a great benefit to know and not have uncertainty."

Finding the gene before a person develops any symptoms opens the door to preventive treatment that could stave off disease indefinitely.

In the past year, three major cardiology societies have highly recommended genetic tests.

Before, only a handful of patients each year with particularly strong family histories underwent such testing. Now, genetic counselor Katie Spoonamore sees a few patients a week, and that's likely to increase.

"What we're trying to do . . . is to make it a routine part of clinical practice," said Dr. Peng-Sheng Chen, director of Indiana University's Krannert Institute of Cardiology.

The test result may influence a patient's care, but for the most part it's about reaching their relatives, who don't know they may have a ticking time bomb in their chest.

"The majority of information is for the family members, about who is at risk," said genetic counselor Katie Spoonamore said. "The whole goal is to pick up someone else before they have major problems."

Typically insurance covers at least part of the cost of genetic tests. It's not uncommon for a person to pay about $100 out of pocket for a $3,000 test.

No matter the result, insurers can't deny a person health insurance. But it could affect a person's ability to obtain life insurance. So genetic counselors advise relatives considering testing to secure a policy before being tested.

If the test picks up a genetic defect, the counselor reaches out to the patient's first-degree relatives, such as parents, siblings and children.

Those who do not carry the gene have no more risk than anyone else in the population. Those who do may start taking medicine or undergoing regular cardiac screenings.

Then there are inconclusive results.

"We all have changes in our genes -- some cause problems and some don't cause problems," Spoonamore said. "Sometimes in cardiac genes, it's hard to determine which type of change we're looking at. That's why counseling is important."

The best-case scenario remains pinpointing the gene. Once that happens, in many cases, doctors can better tailor their treatment to the patient's specific condition.

"Once we identify the gene and know what it does, then you have the unique ability to look at some different interventions that you may not have thought about," Community's Bingle said. "Before, it was more of a shotgun approach. Now you can individualize therapy."

IU's Chen recalled a 40-year-old patient whose two siblings, father, uncle and paternal grandfather died suddenly of heart disease. Ten years ago, the patient opted for an implantable cardiac defibrillator and started on medication to lower her chance of following suit.

Recently, she underwent genetic testing, and after having a positive result, her two children were also tested. One turned out to have the gene; the other lacked it.

Had her doctors known 10 years ago which rogue gene was to blame, they would likely not have recommended the device but would have limited prevention to beta blockers and lifestyle changes, Chen said. (Because removing the defibrillator carries its own risks, it will stay.)

Ten years is a long time in this field. New tests become available all the time. It's now possible to test for about 80 genes that can cause cardiovascular problems.