Cracking your code – Genetic Testing

Genetic testing is no longer the stuff of science fiction, but accessing the secrets of your gene pool isn’t as simple as “just say awww….”

BY MARCIA KAYE

She was only 45 and Kelly Hennessey, the owner of a public relations business in Dartmouth, N.S., had developed breast cancer, just like her mother and grandmother before her. At the time, she suspected she may have inherited a mutation in the BRCA1 or BRCA2 gene, which dramatically increases the chances of getting breast and ovarian cancer. But since she was having a double mastectomy anyway, she pushed genetic testing to the back of her mind. Then, a few months later, her aunt died from ovarian cancer, and everything changed.

Hennessey, a mother of three, felt an obligation to her daughter to investigate their genetic inheritance. “I didn’t want to bury my head in the sand anymore,” says Hennessy, now 51. She contacted her doctor to refer her for genetic testing.

More and more women, concerned about their own and their children’s lifelong health, are following the same route. Ever since Angelina Jolie went public last May about her preventative double mastectomy, many women have wondered, Should I get genetic testing too?

“After Angelina Jolie’s story came out, our phones lit up and were ringing off the hook,” says Katherine Hodson, a certified genetic counsellor in Toronto. But she says there’s still a lot of misinformation out there. Two of the biggest misconceptions are that there’s a catchall test to determine your risk of every disease and condition imaginable, and that you can get the results within a day or two. In truth, the test generally checks for only one disease at a time, and results can take from a few weeks to several months. “Unfortunately it’s not CSI,” Hodson says.

After seven months Hennessey received surprising results: the tests showed no evidence that she carried the faulty gene. Her reaction was mixed. “It gave me a huge piece of hope that I could pass on to my daughter, that she wasn’t destined to get this disease,” she says. But at the same time, it wasn’t a free pass. Her daughter still has the same lifetime risk of breast cancer as the general population—one in nine women, or 12 percent (compared to 45 to 60 percent with the faulty gene). And both of them have the standard 1.4 percent risk of ovarian cancer (versus a 40 to 50 percent risk for those with the BRCA mutation).

“This is what makes genetic testing so alluring,” Hennessey says. “We want it because we can blame the gene. It’s nice and clean and simple and not my fault. And I won’t have to be accountable to my body for all the other things I can control with healthy choices in food, exercise, a spiritual life.” Indeed, it’s believed that faulty BRCA genes, such as Angelina Jolie has, account for only five to 10 percent of all breast cancers.
Genetic testing is a complex, continually evolving field. If you’re considering it, here’s what you need to know.

what genetic testing can (and can’t) do

Genetic testing can screen for thousands of diseases and conditions, such as various cancers, Alzheimer’s Disease, bipolar disorder, macular degeneration, Parkinson’s, celiac disease and even psoriasis and obesity. Depending which condition is being investigated, the test uses blood, saliva or tissue samples to look for genes with sections missing, added or showing too much activity, or chromosomes or key proteins with suspicious physical or behavioural changes.

Despite the advances in genetic research, including the mapping of the entire human genome a decade ago, genetic testing can’t give you a precise forecast of your future health. That’s because researchers have identified only a small fraction of the genetic component of many diseases, and the influences of lifestyle and environment remain major variables. So while it can’t tell you that you will or won’t get a certain disease, it aims to assess your risk.

genetic testing can

• help confirm a diagnosis if you already have symptoms

• evaluate your risk of an inherited disease, such as breast cancer, muscular dystrophy or Huntington’s, before you have symptoms

• show, before you conceive a child, whether you might be a carrier of a disease, such as cystic fibrosis or hemophilia, that you won’t develop but that you could pass on to your children

• show prenatally if a fetus has a genetic condition such as Down Syndrome.

• screen newborns for their predisposition to conditions, such as sickle cell disease or thalassemia.

what’s the process?

Before getting tested, you’ll first see a genetic ounselor to discuss your personal situation. Genetic ounselors are health care professionals with a specialized master’s of science degree. It’s still an unregulated profession, so you’ll want someone who’s certified either by the Canadian Association of Genetic Counsellors or the American Board of Genetic Counseling. Of the 300 certified ounselors in Canada, most work in hospitals and require a physician’s referral, while a few work in private medical or fertility clinics, where a doctor’s referral is recommended but not mandatory.

If you meet certain criteria, such as having family members with a disease, the cost for a consultation will be covered by provincial health insurance, but there may be a lengthy wait time. If you don’t meet those criteria, or don’t want to wait, you can see a private counsellor, which can cost $200 and up, sometimes covered by personal or workplace insurance.

In your hour-long consultation, your genetic counsellor will consider a number of factors before helping you decide if testing is appropriate, but Hodson says, “The single most important thing we use is family history, going back three generations.” You’ll also discuss what you might do with your test results and who you’ll share them with.

If you choose to go ahead with the testing, your counsellor will arrange a doctor’s referral. Again, if you meet certain criteria, which vary from centre to centre, the cost of testing will be covered by public insurance. If you don’t, costs range from a few hundred to several thousand dollars per test.

It’s important to understand that your test results will become part of your medical record. So when you apply for life, health or travel medical insurance, you’re obligated to disclose the results.

Beware of online offers of $99 mail-in genetic tests, whose results are often interpreted not by medical specialists but by computer readings. A New York Times reporter recently had her saliva read by three different direct-to-consumer companies, with wildly differing results.

if the results are negative

You’ll likely breathe a sigh of relief if the test finds no evidence of a genetic problem. But according to Meghan Ferguson, a genetic counsellor in Halifax, “Unfortunately there’s always a little fine print to the good news, because genetic testing is not perfect.” She helps patients understand that the accuracy rate is about 90 percent, not 100 percent, because the testing is so complex. “It’s like looking for a spelling mistake in the Toronto phone book,” she says. She also cautions that a negative test for cancer, for instance, is no guarantee that you’ll never develop the disease from more common, nongenetic causes.

if the results are positive

It’s not necessarily bad news. First, it doesn’t necessarily mean you’ll get the disease. Second, a positive test can sometimes trump the limbo of uncertainty and even be empowering, especially when there are preventive measures you can take.

Dr. Steven Narod, senior scientist at Women’s College Research Institute in Toronto and a world-renowned cancer geneticist who co-discovered the BRCA genes, says, “If a 29-year old woman tests positive for the BRCA mutation, I might suggest she have prophylactic oopherectomy [removal of ovaries] at 35 [after she’s had children], and annual mammograms.” His latest research found that women in Poland with the BRCA1 mutation have only half the risk of developing breast cancer as women in Canada with the same mutation, suggesting that environmental, perhaps nutritional, factors modify the risk.

Positive markers for heart disease, stroke or diabetes can also be modified by not smoking, healthy eating, moderate physical activity and maintaining a healthy weight. While Narod says he’s unenthusiastic about genetic testing for conditions we can’t prevent, such as Huntingdon’s or Alzheimer’s, Hodson suggests the knowledge may help you prepare for the disease or make different life choices.

Ultimately, the decision around genetic testing is not your doctor’s or your counsellor’s—it’s yours, so you need to make sure you’re prepared for the results. “We will never make that decision for you,” Hodson says, “but we’ll support you through the process.”