Live

Watch CBSN Live

Gene Tests Rate Sudden Cardiac Death Risk

New genetic studies are being made available to doctors and patients every day.

To kick off our "Early Show" series, "What's in Your Genes?" CBS News medical correspondent Dr. Jennifer Ashton took a look at some of the genetic advances being made -- and the medical battles that are being won.

Since mapping the human genome was completed in 2003, Ashton said researchers and doctors have found ways of translating discoveries into clinical applications to benefit patients. Now once hard-to-detect diseases are being treated.

Sharon Brown, a breast cancer survivor, recently visited the Mayo Clinic in Rochester, Minn. to undergo a new round of clinical tests for Long QT syndrome, a rare heart disease that affects one in 4,000 Americans. Ashton pointed out the first sign of the disease often is very severe: sudden cardiac death.

Brown's father died at age 56 of a heart attack, and her grandfather died of a heart attack, as well. But today, Ashton said, doctors can combine Sharon's family history with genetic testing to better determine her risk for having the disease.

Dr. Michael Ackerman, a pediatric cardiologist at the Mayo Clinic, said, "We are really now doing personalized genomic medicine for this disease of Long QT syndrome."

Ackerman was one of the people who helped develop the genetic test, from which he and the Mayo Clinic share a financial interest.

"It really has been a wonderful story, from bench discovery to translation to patient and to actual availability to patients," he said.

Ashton said this genetic test may save Brown's life, because her results identified a mutation on chromosome 3 and the SCN5A gene -- a marker for type III Long QT syndrome.

And because the disease is hereditary, Brown's children are being tested, as well.

Ackerman said, "We found the cause -- this X marks the spot -- now it actually becomes simple for her two sons to see if they are among the haves or the have-nots."

For Brown, discovery of the gene linked to her family's deadly disease means a step in the right direction for her children.

"If they do have it," she said, "I am confident that they can be treated and can live normal lifestyles, and that's what is so wonderful about genetic testing. ... I feel fine and very confident that I'll be around when I'm 56, and 66, and when I'm 76."

Treatment for Brown will likely include surgery for an implantable cardioverter defibrillator, also known as an ICD, to control the rhythm of her heart.

Ackerman said, "Really, in 2009, if we do it right sudden death from this disease should be the exception, rather than the rule."

He added it's success like this that is driving genomic research even further.

Ackerman said, "The genomic floodgates have opened wide."

Ashton reported researchers believe targeting specific diseases will give way to mapping an individual's entire genetic code, which could lead to a longer, disease-free life.

"We won't have 'the human genome' project," Ackerman said. "We'll have 'your genome' project, and mine. And there will be no genetic test in a dozen years for cystic fibrosis and Long QT syndrome, because they will all be on your genetic thumb drive."

Exactly when the personal genome project will be discovered is open to debate, Ashton said.

However, Ashton remarked there are some drawbacks to the genetic testing.

"Genetic testing provides just one piece of the puzzle," Ashton said. "(It) doesn't tell us how that genetic result will react with things like the environment."

Ashton said the results have to be interpreted.

She added it's not just the matter of getting the results. Other factors, Ashton explained, including privacy and discrimination issues could result from the testing.

Ashton said, "We're going to see a lot more of this in the future."


For more information on Long QT syndrome, got to the Mayo Clinic site by clicking here.

To visit The Sudden Arrhythmia Death Syndromes (SADS) Foundation.