It can be difficult to interpret prenatal extended carrier screening tests: shots

It was not difficult for Shara Watkins to get pregnant. It was hard for her to stay pregnant.

In 2016, she was devastated by two miscarriages. With the help of several medications, she managed to carry a child last year.

Shara and her husband, Robert, were delighted when she reached her second trimester, the phase where the highest risk of miscarriage faded.

Unfortunately, the struggles of the San Mateo couple in California continued.

Shara spent four months of her pregnancy at rest. When their doctor offered them extensive genetic tests to check the health of their fetus, the couple jumped on the occasion. Shara had a history of rare illness in her family.

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

Overabundance of information available for prospective parents

In the past, doctors had been able to screen parents for some suspicious diseases common to their ethnicity or family history. But now, a growing number of companies are offering in-depth testing panels for hundreds of rare diseases.

"In the last 10 to 20 years, the number of genetic disorders that we are able to test has exploded," says Dr. Mary Norton, a prenatal geneticist at the University of California at San Francisco.

Silicon Valley is a home for businesses vying for prospective parents. The prenatal genetic testing industry is expected to grow by almost 30% over the next five years.

A wide variety of tests are now available for fetal and parent screening. An option whose popularity continues to grow is called extended filtering of carriers.

A dozen labs, most of them based in the San Francisco Bay Area, can analyze a patient's blood or saliva to detect hundreds of illnesses their child may inherit.

A parent in perfect health can transmit an autosomal recessive disorder such as cystic fibrosis, fragile X syndrome or Tay-Sachs disease, if his partner is also a carrier of the disease. When both parents have a mutated version of the same gene, their child has an increased risk of developing a disease.

"In these types of diseases, there is no family history in 80% of cases," said Jim Goldberg, chief physician of Myriad Women's Health. Norton agrees that family history is not a very sensitive screening tool.

The ideal time to screen carriers is before conception, because in vitro fertilization is still possible.

If it turns out that both parents carry the same disease, IVF allows doctors to guarantee the health of a fertilized egg by performing a genetic screening of the embryos before conception.

The tests must be prescribed by a doctor and the prices of the screening panels vary considerably. For example, a customer service call from the Myriad Genetics lab located in South San Francisco resulted in an estimate of US $ 1,599 for uninsured patients.

But if you pay within 45 days, the price drops to $ 349. Shara and Robert paid about $ 600 for their two selection panels from a Bay Area company called Natera. The company billed their insurance at about $ 3,200 for both tests.

Does knowing more help?

When Shara's doctor and Rob sent the results of their analyzes by email, the couple worried because their doctor had suggested they see a genetic counselor to help them interpret the report.

"This new landscape is complicated and most OB-GYNs do not have the ability to understand it themselves and explain it well," says Norton of UCSF.

It appeared that Watkin's baby could inherit spinal muscular atrophy, or SMA, a life-threatening illness. The couple had not discussed what he would do if his child was in poor health.

"I called Rob in pure hysteria on the way to work," says Shara.

"When I got the call in my office, she was crying," Rob remembers. "We were immediately in panic mode."

Rob and Shara spent the day browsing page after page the test results, and then the next days searching for answers on the Internet.

"The test results somehow give you these alerts on the front page, as if you were a carrier for this, your carrier for that," Shara said. "It's really unclear – I mean, if it had been clear, we would never have gone into full panic mode."

Find an expert

Although Shara and Rob could have asked for free advice from one of Natera's genetic counselors, they chose an unaffiliated expert. They booked the first available appointment at Stanford Children's Health. Stanford charged $ 642 to Shara's insurance for the consultation. His plan paid $ 352.

"They provided us with this information without knowing what it meant, what the risks were, or understanding the implications," said Meg Homeyer, Genetics Counselor at Stanford. "Moreover, the language is difficult to interpret and can sometimes seem alarmist."

In fact, Shara, Rob and their doctor thought their baby's ADM risk was much higher than it was. The report says that they were exposed to an increased risk of carrier, but this is not the same as being a real carrier of the disease.

"It was much lower, closer to 3,500," says Homeyer flipping through the test results. Yet even though Rob and Shara's worst fears did not materialize, they still lost sleep at night wondering if their child could be the 1 in 3.500.

Give meaning to the risks

Homeyer says that she often sees parents getting embarrassed about how to feel, or whether to act on abstract numbers.

"They will not know if a baby is 100% healthy until birth," Homeyer said. "In the meantime, they are trying not to worry about the risks, but they can not stop it."

Homeyer says that the value of a test depends on the values ​​of an individual couple.

"Some family members will want to have all the tests possible," Homeyer said. "They will not want to know anything because their risk tolerance is low.There are other families where this information during pregnancy is not helpful to them."

Like families who would not ask for other diagnostic tests or who could eventually terminate a pregnancy, regardless of the test results.

"We often have people who say," I would have liked never to have taken this route, "says Norton." Although I do not think people can really anticipate what they'll feel up to. " They arrive there. "

One test leads to the other

For those who choose to do carrier screening, the worst case is that their child has 1 in 4 chance of inheriting an autosomal recessive disorder. Other invasive diagnostic tests, such as an amniocentesis, are needed to confirm this possibility. Fortunately, care for rare diseases has improved considerably in recent years.

"Many more of these conditions are treatable after birth," says Norton. "And treatment starting at birth can improve the results, and in some cases we can even start treatment during pregnancy."

Norton said that the advent of more advanced tests was raising a lot of fear among practitioners that the abortion rate would increase simultaneously, but that's not what preliminary studies show.

Why search for more diseases is not always better

If you are the type of parent who wants as much information as you can, you may be inclined to take the most comprehensive test on the market. However, UCSF director of genomics Aleks Rajkovic warns families who are attracted to many panels.

"Many of them are exaggerated," says Rajkovic. "Some panels test for very rare disorders that have been observed only in one family, so the likelihood that a client will actually have the variation is infinitely small."

In addition, he says that extremely rare diseases are generally not well studied or understood, so it is very difficult for doctors to give useful information about the possible consequences of a prognosis.

A happy ending

Fortunately, Shara's little girl, Kaiya, is five months old and healthy. When asked if Shara would like to come back and repeat the genetic test, she pauses and then nods her head.

Although she has spent months worrying about the minimal possibility that her child is not well, she says that the anxiety she faced was better than knowing nothing at all. His advice to future parents is to think carefully about whether more information will reassure them or if it is just another thing that worries him.

Norton agrees. She hopes that families will focus on one essential fact: 97% of babies are born in perfect health.