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The Quandary of Genetic Testing When You're Pregnant

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Monday, February 11, 2019

It wasn't hard for Shara Watkins to get pregnant, it was hard to stay pregnant. In 2016, she was devastated by two miscarriages. Finally, through the the aid of several medical interventions, she and her husband Robert successfully conceived again last year. They were elated when she reached her second trimester, the phase when the highest risk of miscarriage subsides.

Unfortunately the San Mateo couple's struggles continued. Shara spent four months of her pregnancy on bedrest, so when their doctor offered extensive genetic testing to check the health of their fetus, the couple leaped at the opportunity. Plus, Shara had a history of rare disease in her family.

“I had a high-risk pregnancy, and there had been a lot of complications prior to this," says Shara. "And, so I just wanted to have all the information that I could.”

Information Available to Expecting Parents Balloons

In the past, a doctor may have screened a parent for a few suspect diseases common to their specific ethnicity or family history, but now a growing number of companies offer extensive panels testing for hundreds of rare diseases.

"Over the last 10 to 20 years the number of genetic disorders that we are able to test for has exploded," says Mary Norton, a prenatal geneticist at UCSF.

Silicon Valley is a hotbed for companies vying for the business of concerned future parents. The prenatal genetic testing industry is projected to grow nearly 30 percent over the next five years. A wide variety of tests are now available to screen both fetus and parents. One option that's rapidly growing in popularity is called an expanded carrier screening.

About a dozen lab companies primarily based in the Bay Area can scan a patient's blood or saliva for hundreds of conditions that their child could inherit. A perfectly healthy parent can pass along an autosomal-recessive disease like cystic fibrosis, Fragile X syndrome or Tay-Sachs, if their partner is also a carrier for the disease. When both parents have a mutated version of the same gene then their child is at an increased risk for developing a condition.

"In these types of diseases 80 percent of the time there's no family history," says Jim Goldberg, Chief Medical Officer of Myriad Genetics. Norton agrees that family history is not a very sensitive screening tool.

Carrier screening tests must be prescribed by a doctor and panels very widely in price. For example, if you call the customer service line for Myriad Genetics lab in South San Francisco a representative will quote a price of $1,599 for patients who do not have insurance. But if you pay within 45 days the price drops to $349. Shara and Robert paid about $600 out of pocket for their two screening panels from a Bay Area company called Natera. The company billed their insurance more than $30,000 dollars for both tests.

Does Knowing More Help?

When Shara and Rob's doctor emailed over their tests results the couple was alarmed because their physician suggested they see a genetic counselor to help them interpret the report.

"This new landscape is complicated and it's beyond the ability for most OB-GYN's to really understand it themselves and explain it well," says Norton.

It appeared the Watkin's baby could inherit spinal muscular atrophy, or SMA, a potentially fatal disease. The couple hadn’t discussed what they would do if their child was unhealthy.

“I called Rob in pure hysterics on my way to work,” says Shara.

“When I got the call in my office she was crying," recalls Rob. "We were both in kind of a panic mode immediately.”

Rob and Shara spent the day pouring over page after page of testing results, and then subsequent days searching the internet for answers.

“The test results give you kind of these alerts on the first page like you're a carrier for this, your carrier for this," explains Shara. "It's definitely not clear. I mean, if it had been clear we wouldn't have ever gone into full panic mode.”

Find an Expert

Although Shara and Rob could have sought free counseling from one of Natera's genetic counselors, they chose an unaffiliated expert. They booked the first available appointment at Stanford Children's Health.

“They came to us with this information not knowing what it meant, not knowing what the risks were, and not understanding the implications,” says Meg Homeyer, a genetic counselor at Stanford. "Plus, the language is difficult to interpret and sometimes can sound alarmist."

Shara and Rob thought the test results indicated their child could have a one in four chance of inheriting SMA because the report says they were at an increased carrier risk, however, that is not the same thing as being an actual carrier for the disease.

“It was much more lower more like 3,500," says Homeyer as she thumbed through the test results.

Yet, even though Rob and Shara’s worst fears didn't play out, they still lost sleep at night wondering if their child could be the one in 3,500.

Making Sense of Risks

Homeyer says she frequently sees parents agonize over how to feel, or whether to act on abstract numbers.

“They will not know whether a baby is 100 percent healthy until birth," says Homeyer. "In the meantime they're trying not to worry about the risks but they can't help it."

Homeyer says the value of a test is dependent on the values of an individual couple.

“There's the family that will want every possible test available," says Homeyer. "They'll want no stone unturned because their tolerance for risk is low. There are other families where this information in pregnancy isn't useful for them.”

Like families who would not seek further diagnostic testing , or potentially terminate a pregnancy regardless of testing results.

"We often have people who say, 'I wish I had never started down this path,'" says Norton. "Although I don't think people can really anticipate how they'll feel until they get there."

One Test Leads to the Next

For those who choose to do a carrier screening, the worst case scenario is their child has a one in four chance of inheriting an autosomal recessive condition. In that case, further diagnostic invasive testing like an amniocentesis is necessary to confirm the possibility. Fortunately care for rare diseases has improved dramatically in recent years.

"Many more of these conditions are treatable after birth," says Norton. "And treatment starting right at the time of birth may improve the outcomes. In some cases we can even start treatment during pregnancy."

Norton says the advent of more advanced testing stirred a lot of fear amongst practitioners that abortion rates would simultaneously rise, but that's not what preliminary studies are showing.

Why Scanning for More Diseases Isn't Always Better

If you're the type of parent that does want as much information as possible you may be lured to take the most comprehensive test on the market. However, Aleks Rajkovic, Chief Genomics Officer at UCSF, cautions families attracted to extensive panels.

"A lot of them are overkill," says Rajkovic. "Some panels are testing for very rare disorders that have only been seen in a single family, so the likelihood of a client ever actually having the variation is infinitely small."

Plus, he says extremely rare disease are usually not well studied or understood, so it's very hard for doctors to offer helpful information about what a prognosis could entail.


A Happy Ending

Fortunately Shara's little girl, Kaiya, is a healthy five-month-old. When asked if Shara would go back and take the genetic test again, she pauses, but then nods yes. Even though she spent months fretting over the tiny possibility her child wasn't ok, she says the anxiety she dealt with was better than not knowing anything all. Her advice to future parents is think carefully about whether more information will, for them, be reassuring or just another thing to worry about.

Norton agrees. She hopes families focus on a key fact: 97 percent of babies are born perfectly healthy.

Author: Lesley McClurg
Source: KQED
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