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Genes: Your body's crystal ballGenetic science is racing ahead toward a day when doctors will be able to predict what diseases you're susceptible to. But do you really want to know?By Ronald Kotulak
Tribune science reporter
Published June 26, 2005Doctors can now take a few of your cells, pull out the DNA, stretch it across a screen and diagnose more than 1,100 genetic defects that could mean trouble, ranging from rare disorders to more common ones like heart disease and cancer.
Surprising even the experts, genetic testing is racing ahead faster than doctors, genetic counselors and others can keep pace, driven by scientists eager to claim the prize of predicting diseases before they happen and perhaps preventing them.
The potential of the field raises questions for a public wary of peering into the genetic future and jaded by unfulfilled medical promises. How will people handle the news that ticking away in every cell of their body are potential disease genes inherited from their parents, which they in turn may have passed on to their children?
And everybody has them. Geneticists estimate that each person may have more than 30 genes that make them susceptible to a variety of disorders. A person's risk of developing a specific disease depends on which genetic combination he or she possesses in conjunction with environmental stressors arising from lifestyle choices or chemical exposure.
"Knowledge is a good thing when you can use it productively," said Dr. Wylie Burke, chief of medical history and ethics at the University of Washington. "But sometimes it's not a good thing. This whole genetic risk era is going to push us to think very carefully about that."
Many people are especially concerned about genetic discrimination--using abnormal genes to deny jobs or health insurance--and tests for genes that cause deadly illnesses for which there currently is no treatment, such as Huntington's disease.
A test for the Huntington's gene has been available for a decade, but it has been shunned by people at risk--children of parents with the disease--who don't want to live for years knowing the illness will start destroying their brain in midlife. And although an eight-year-old test can identify a gene associated with Alzheimer's disease, few physicians offer it to patients out of fear they might become despondent.
Still, some recent studies suggest people might be more willing to take the news in stride and act on it, especially if they are told the difference between a gene that causes a disease 100 percent of the time--as with Huntington's--and a gene that only increases their susceptibility, which is far more common.
Children of Alzheimer's patients whose genes were tested overwhelmingly accepted the genetic findings without becoming depressed or anxious, Dr. Robert C. Green of the Boston University School of Medicine reported last week at an Alzheimer's conference in Washington, D.C.
[see this article which describes a study where knowledge of increased risk of Alzheimer's causes no increase in depression or anxiety among children of people with Alzheimer's]Acting on genetic dataThose with the faulty gene also took steps to reduce their risk of contracting the disease, including exercising more, eating better, taking vitamins and engaging in mentally stimulating tasks, he said. "We found that learning you had a genetic risk marker made this more real to people and made them want to act on it," Green said.
Genetic testing was once mostly limited to newborns and people with single-gene disorders like Huntington's, but with the discovery in 1994 of two breast cancer genes, BRCA 1 and 2, the field rapidly expanded into the common adult killer diseases.
Between 1993 and 2004, gene tests jumped more than eleven-fold to 1,148, and the number of laboratories offering genetic testing increased more than fivefold to 577, according to the University of Washington's GeneTests Laboratory Directory, a federally supported agency that lists available genetic tests.
Genetic testing costs anywhere from a few hundred dollars to thousands per test. Many health insurance companies pay for them, depending on the type of coverage.
New era in medicineScientists are racing to discover disease-related genes because they promise to open a new era of predictive medicine, where each individual will eventually know the genes that increase his or her risk of illness, and what they can do to head off those health problems.
"In the next three or four years there's going to be an absolute outpouring of discoveries about gene variances that are associated with the risk of diabetes, heart disease, cancer, asthma, high blood pressure, mental illness and other conditions," said Dr. Francis Collins, director of the National Human Genome Research Institute.
"It will allow us to individualize programs of preventive medicine so that you could plan your own diet and lifestyle and medical surveillance based upon your genetic risks as opposed to some broad generic prescription of activities, which is what we currently do," he said.
"The argument against genetic testing was really, `Well, what are you going to do about it?'" said Dr. Olufunmilayo Olopade, director of the University of Chicago's Center for Clinical Cancer Genetics. "But I think cancer presents a unique opportunity for us because we know we can cure some cancers. We can prevent them."
Gene tests are available, for example, to diagnose people at risk of developing thyroid or colon cancer in their 30s or earlier. These cancers can be prevented through the removal of the thyroid or regular screening to remove polyps from the colon, Olopade said.
When Julie Spiekhout was diagnosed with breast cancer in August, she decided to have a genetic test and found she carries the BRCA 2 gene.
That information persuaded Spiekhout to have her ovaries removed, since the gene also increases the risk of ovarian cancer. The disease is difficult to diagnose early enough for a cure, and two of Spiekhout's aunts died of it.
Spiekhout, who is being treated at Northwestern Memorial Hospital, also plans to discuss the BRCA 2 gene with her 8-year-old daughter, sister and cousins so they can start mammograms early to detect breast cancer in its most curable stage or prevent it with drug therapy.
"Being diagnosed with cancer used to just be a death sentence," said Spiekhout, 39, of Highland, Ind. "Now, I never even thought that. My first thought was, what do I have to do to fight this? Give me the information I need and I'm going to do whatever I need to do."Susceptibility genes, such as the BRCA genes and the one linked to Alzheimer's, indicate a level of risk rather than a foregone conclusion, Green said.
"They're sort of like finding out you have elevated cholesterol," he said. "It increases your chance of getting a disease, but it doesn't mean you're definitely going to get it."
People who have one copy of the Alzheimer's gene, ApoE4, are three to five times more likely to get the disease than people without it, Green said. Those with two copies are 20 to 30 times more likely to get it.
The study presented last week involved 162 people who had a parent with Alzheimer's disease. Half were told their genetic risk and the other half were not. A year later, there was no difference psychologically between the groups, Green said.
"Under carefully controlled circumstances, we are showing that people are handling information about susceptibility genes very well," Green said.Yet considerable uncertainty remains about the public's willingness to accept genetic testing or how they will react.
`People react differently'Dr. David Rubin, director of clinical education for gastroenterology at the U. of C., said some people at risk for a genetic disease grieve when told they don't have the gene. They suffer guilt at not being affected when other family members are.
"People react differently," said Kelly Ormand, director of the graduate program in genetic counseling at Northwestern University's Feinberg School of Medicine. "Some see genetic knowledge as valuable and that it gives you options and allows you time to prepare if you need to prepare for something like Alzheimer's disease.
"There are some people who just don't want to know," she said. "They believe it will make them anxious. `There's nothing I can do about it. What happens, happens.'"
Experts also are concerned that the rate of progress in discovering new disease genes is outpacing medicine's ability to use them to help patients.
"Some discoveries are so new we don't know how to use them yet in our practice," Rubin said. "You have a generation of physicians in practice who only learned simple genetics and haven't been able to keep up with some of the more complex advancements. [Sounds like they better get 'busy' then...-KP]"It also takes time to gather a complete family history of disease and know what to do with it," he said.
"Genetic counselors are in short supply and we're going to need more of them to help us understand how to interpret risk and what to do with it."Federal law proposedAs genetic tests for common diseases become increasingly available, a backlash may build up if federal legislation is not passed to prohibit genetic discrimination, Collins said.
HIPPA, a federal law limiting access to medical records, provides genetic privacy for people with group health insurance. But for the growing number of people who have to obtain individual policies, there is no protection, he said.
A number of states, including Illinois, have passed anti-genetic discrimination laws, but they are usually too weak to provide adequate protection, Collins said. In February the U.S. Senate unanimously passed a bill that would ban discrimination against people because of their genes. But the proposed legislation has stalled in the House, Collins said, because of strong objections from the health insurance industry and the U.S. Chamber of Commerce.
"The promise of genetic testing, which has a great deal of potential to keep people healthy and treat disease more effectively, could end up just not happening because of people's fear that this kind of information will be used against them," he said.
Families can consider compiling their own information about family diseases.Paula Cardinale of Hammond knew that a gene for colon cancer had been found in a second cousin, but two years ago, at age 29, she thought the disease was "an older person's problem."
Then a pain in her side led her to have a CT scan, which disclosed a large mass that turned out to be colon cancer. A blood test would reveal she had the mutated gene hMLH1 that leads to the development of colon polyps, which quickly turn cancerous, before age 30.
"It's been a huge relief for me," said Cardinale, who is being treated at the University of Chicago. "I feel like I have more control of a very scary situation. They have specific screening for me to go through to protect myself because early detection is lifesaving."
Cardinale, who now undergoes regular checks but is cancer free, knows her children, Gina, 4, and Joey, 2, have a 50 percent chance of having inherited the faulty gene.
"What this has taught me is how I'm going to raise my children to think of gene testing and screening," she said. "When you find something like that in your family, it should just be known simply as preventive maintenance to keep you healthy, like getting your teeth cleaned twice a year."