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Continued: With genetic testing, patients can see the future

  • Article by: ALLIE SHAH , Star Tribune
  • Last update: January 20, 2014 - 9:06 AM

Direct-to-consumer genetic test kits are not covered. Hundreds of thousands of people have used 23andMe, which analyzes a segment of a person’s DNA sequence for genetic alterations linked to cystic fibrosis, sickle cell anemia and even breast and ovarian cancer. But critics — including the U.S. Food and Drug Administration — say the test is limited in its ability to diagnose health risks accurately and could lead users to undergo unnecessary medical procedures. FDA officials recently ordered 23andMe to halt marketing its DNA test kits.

What can a test reveal?

For someone with a defined disease, the use of genetic testing can be very effective in determining what medicines work best in treatment, doctors say.

A 44-year-old woman with gall bladder cancer is among the success stories at the Mayo Clinic’s Center for Individualized Medicine, said Dr. Alexander Parker, the center’s associate director. Her tumor was not responding to the standard medicine used to treat gall bladder cancer. Through genetic testing, doctors discovered that drugs used on leukemia patients might work for her. They tried it, and her tumor started to shrink, Parker said.

But for healthy people whom he calls the “worried well,” there is little to no value in having your genome mapped. It may cause harm by raising anxiety about the odds of developing a disease.

“At the end of the day, this is about risk,” Parker said. “While we all want definitive answers to everything, the beautiful thing about our world is that there is random chance. Because of that, we can never say 100 percent that we know exactly what will happen to anyone.”

What factors should go into your decision to get a test?

Parker encourages those curious about genetic testing to have a conversation with their primary doctor first. Ask: “Is there any value in this for me?”

Genetic counselors also play a key role in helping reach a decision. They typically hold master of science degrees in programs that include training in medical genetics and counseling. They work in consultation with doctors, nurses and other health professionals.

Truelson said she encourages patients to ask these questions: What type of information will the test give me? How will this affect me from a medical standpoint? How will this affect me from an emotional standpoint?

Nada Maalouli, of Eagan, has wrestled with these questions for years. Her mother died of ovarian cancer before she reached menopause. Her grandmother and an aunt on her mother’s side died of breast cancer. Maalouli worries she may be next. A genetic test would tell her if she carries a mutant gene associated with higher risks of breast and ovarian cancer.

She has agonized over the decision to get tested, in part because she fears the test for breast cancer would be positive.

“I don’t know if I can live with that,” she said. “I feel like maybe it will [make] me depressed.”

She has visited a genetic counselor three times in the past 10 years to weigh the pros and cons. At 51, she and her three sisters — all healthy so far — have made a pact. They will get regular mammograms and MRIs, and if any of them detects that there is something wrong, then the sisters will all go in for genetic testing.

How will testing affect your family?

One person’s choice to get tested may also reveal health information about your relatives, who may prefer not to know, Truelson said.

For Keegan, who visited Mayo from Ohio, the decision to have his genome mapped affected several members of his family. Mayo doctors asked his older brother and father also to submit a DNA sample to find out if Keegan had inherited his father’s disease. Keegan’s father previously had a kidney transplant.

In addition, Keegan and his wife were thinking about starting a family and wanted to know what their chances would be of passing on the mutant gene. Turns out there is a 50 percent chance their offspring will inherit it. For the couple, the test results have led to many discussions about having children.

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