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Mysterious deaths tied to hereditary heart disease

Posted - Jul. 30, 2004 at 11:20 a.m.



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Knight Ridder Newspapers

(KRT)

SAN JOSE, Calif. - On a cold winter Sunday in Virginia, a young woman swings a shovel at a pile of snow and collapses, her heart failing. Her sister takes a call with the startling news and blacks out. Her heart has stopped, and paramedics can't restart it. The two die within hours of each other.

The deaths of Ann Dotson and Patti Mendes in January 2000 would have seemed a frightening coincidence, until genetics entered medicine. Now doctors know that the same legacy claimed their lives: inherited Long QT Syndrome.

"There are no words for what happened that day," said Lori Myers-Jantz, their sister. "You can live with this and never know it's there."

In their unmasking of Long QT, geneticists are finding new answers for families stricken by unexplained health problems and deaths generation after generation. Their discoveries reach beyond Long QT into different types of irregular heartbeats, or arrhythmias, and other secrets of the heart.

"People talk about Long QT as the Rosetta stone of genetic research into cardiac arrhythmias," said Dr. Stephen Hammill, president of the Heart Rhythm Society, a medical association. "It's where things started."

Long QT Syndrome is a disorder of the network of electrical impulses that controls the heart's pumping.

An electrocardiogram, a test to trace the heart's rhythm, measures these rapid impulses, tracking them in five waves labeled P-Q-R-S-T.

The timing from "Q" to "T" is a crucial step. If that interval takes longer than normal, the heartbeat is vulnerable to a rapid, uneven rhythm. A person's heart may race, unable to pump blood, causing fainting, cardiac arrest or death.

Long QT is almost always genetic. Mineral imbalances and some medications also may trigger Long QT, although doctors increasingly think genes may play a part in many such cases, too.

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The syndrome affects people of any age, gender and race. It has been linked to some cases of sudden infant death syndrome, in which babies die without warning. Coroners are participating in studies to see whether unexplained drownings or other sudden deaths, especially in younger people, are due to Long QT.

Genetics also may influence arrhythmias in more subtle ways. In one recent study, doctors at the Mayo Clinic in Rochester, Minn., ran genetic tests on more than 700 ethnically diverse volunteers without any sign of Long QT Syndrome. They were looking for significant variations in genes that affect heart rhythm.

What they found caught the attention of heart specialists. In the study, one in four blacks and one in seven whites had a least one such genetic variation.

Those variations may not lead to full-blown Long QT. But they might make a person more vulnerable while taking a certain medicine or cause a quicker death during a heart attack.

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As genetic medicine has revealed a key cause of Long QT, the syndrome "is trying to teach us about the bigger picture," said Dr. Michael Ackerman, a Long QT expert who led the Mayo Clinic study. "Why does one heart attack patient die and the other thrive? What answers are in the Long QT story?"

Doctors also are exploring why Long QT is sometimes fatal. Some people with Long QT never show signs of heart trouble. Many will suffer some type of cardiac event, such as a faint, but recover on their own without permanent damage; about 4 percent to 5 percent of people with inherited Long QT suddenly die.

After Myers-Jantz lost her sisters Ann and Patti, genetic tests revealed that she, Ann, and four of her surviving siblings had Long QT mutations. It is likely the abnormality also affected Patti and another sister, Michelle, who had died suddenly of heart-related trouble more than 20 years earlier. The gene was inherited from their father, the family learned. Further study showed Myers-Jantz had passed the gene on to her youngest son.

Both the 40-year-old teacher from the and her teenage son have had defibrillators implanted to shock their hearts back to normal if they go haywire.

"At school, people call me `Electric' and all kinds of things," Myers-Jantz said. "But that's not a problem. I feel very blessed we have this technology."

She also knows she is not alone. Another teacher at her school has lost a relative to Long QT. Myers-Jantz urges people with a history of unexplained fainting or sudden death in their family to ask questions, get checked - and not be afraid.

"I'm lucky. I've been blessed with answers," she said. "You can have Long QT, and you still have to celebrate life."

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Who may be at risk:

-People with unexplained fainting during physical exertion or emotional excitement or agitation.

-People with unexplained fainting after being startled, especially by sudden sounds such as ringing phones or alarm clocks.

-People with any history of unexplained fainting or in their family.

-People with a history of sudden death in their family, especially in young people.

-Relatives of people with diagnosed Long QT Syndrome.

Commercial genetic testing:

Familion, a test for Long QT offered by Connecticut-based Genaissance Pharmaceuticals, became available in 45 states in May.

The test uses blood samples and takes four to six weeks, checking for mutations in five known Long QT genes. Genaissance officials say the test is sensitive enough to detect Long QT mutations in 75 percent of patients with Long QT genes.

The test costs $5,400 for the first family member suspected to have Long QT, and $900 for each additional family member. Genaissance helps patients get coverage from their insurance company.

For more information, call Genaissance at 866.326.4546, or go to www.familion.com

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(c) 2004, San Jose Mercury News (San Jose, Calif.). Distributed by Knight Ridder/Tribune News Service.

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