Can You Tell if Your Baby Has Autism Before Birth
When Maureen Bennie's son, Marc, was 10 months sometime, he started missing developmental milestones. He had had feeding problems since nativity and developed a sleep disorder — and Bennie quickly grew concerned. "I had friends who had children around the same fourth dimension," she says. "He really was a very, very different infant in all regards."
Bennie took Marc to see a dr. but did not come up habitation with a clear diagnosis. And when she got pregnant again when Marc was 17 months onetime, it didn't cross her mind that the kid she was carrying might face similar challenges. Marc'south autism diagnosis was confirmed when he was almost 3. His babe sister, Julia, was diagnosed nearly a twelvemonth subsequently at 23 months. "You merely tin't believe information technology's happening the 2d fourth dimension around. You call up: what are the chances?" says Bennie, who later founded the Autism Awareness Eye Inc, a company based in Canada.
Bennie wasn't aware then that autism ofttimes recurs in families: Infant siblings of autistic children are near 20 times more probable than the general population to be diagnosed with the condition. Bennie's children were built-in in the 1990s, and it wasn't until the following decade that scientists learned about baby siblings' high odds. Had Bennie known that Marc has autism before her second pregnancy, she says, she might have avoided getting meaning again.
These days, with easy access to the facts almost autism'due south recurrence and, increasingly, to tests that can notice some mutations associated with autism in fetuses, parents like Bennie are facing difficult decisions. Some parents see any knowledge about their unborn child as a bonus, and they welcome the opportunity to prepare for a kid on the spectrum — and mayhap to begin therapies early. But others may worry they are ill-equipped to take on the responsibility of raising a child with developmental challenges. They may determine to take fewer children after having a child with autism or even to terminate a pregnancy based on the results of a prenatal test. In surveys, women describe these decisions as "tortured" and talk about a "frenzied search" for more information.
For now, though, the decisions are not based on solid facts: The information prenatal screens such as ultrasounds provide nearly autism is incomplete and tin only hint at a heightened risk. I 2016 study, for example, linked kidney abnormalities on an ultrasound to the possible presence of microdeletions in 17q12, a chromosomal region linked to autism. Another written report, published earlier this year, found links between backlog brain fluid and mutations in SCN2A, a leading autism gene. Neither of these associations has been proven, however, so these parents should seek confirmation with tests that detect mutations, says Ronald Wapner, director of reproductive genetics at Columbia University's Plant for Genomic Medicine, who led the brain-fluid study. "Nobody should make a decision based on just a screening examination; they should all have the diagnostic exam," he says.
Diagnostic tests also, though, are less than definitive because researchers are withal trying to understand how any given mutation might atomic number 82 to autism. "Most autism is probably polygenic, significant there are many, many genes contributing to it," says Neil Risch, a genetic epidemiologist at the Academy of California, San Francisco. Even if ii people carry the aforementioned genetic variant, "one may have a very severe syndrome and the other much milder — or no syndrome at all," he says. Some parents report feeling "even more uninformed" after chromosomal microarray testing, which tin detect some variants linked to autism, he says.
Expectant parents can opt to sequence the whole genome of the fetus, obtained through invasive procedures such as amniocentesis or chorionic villus sampling, or via noninvasive prenatal testing. Almost invasive procedures crave doctors to insert long needles into a significant woman'south belly to obtain genetic material from the fetus — and and then they raise the take chances of miscarriage. By dissimilarity, nonivastive tests demand only a uncomplicated blood depict from the mother and pose no risk to the fetus.
For now, the question of which technique to use to sample fetal Deoxyribonucleic acid is moot because the American Higher of Obstetricians and Gynecologists does not recommend whole-genome sequencing for prenatal diagnoses, other than for enquiry purposes. Plus, "it's expensive and it takes time, and specialized people are needed for interpretation," says Diana Bianchi, director of the Eunice Kennedy Shriver National Institute of Kid Health and Man Evolution. However, genome sequencing is likely to become more than common as its cost drops and more people gain access to noninvasive tests.
When that happens, experts warn, it is likely to bring with it a host of thorny problems. Some say the tests may pb to more terminations — to the detriment of a society'south neurodiversity. In Iceland, for example, only nearly two children with Downward syndrome take been born each twelvemonth since the introduction of prenatal tests for the syndrome in the early 2000s.
The more sensitive prenatal tests for autism become, the more than likely they are to present families with increasingly challenging dilemmas. "What should we exam for? What should we not test for?" Wapner says. "As our tools get better, these questions become more important; that'due south all worthy of a very difficult give-and-take."
Sensitive tests:
Before the introduction of noninvasive tests in 2011, many pregnant women skipped prenatal Dna testing because of the risks involved — unless they were older than 35 or had a family history of sure genetic conditions. Noninvasive tests analyze the mother's blood to isolate fragments of placental DNA, which is usually identical to the fetal DNA. Since the tests were introduced eight years ago, employ of the invasive screening methods has dropped — past more than 40 per centum from 2013 to 2017 in New York Urban center, for example.
A noninvasive test for Down syndrome is highly authentic: Its sensitivity and specificity are both to a higher place 99 percentage. But the usefulness of noninvasive prenatal testing for autism is express. Some commercial labs offering the tests claim they tin screen for mutations in a range of genes, including some related to autism. But merely "a very minor percentage of cases of autism" could be identified this way, Wapner warns.
These noninvasive tests entered the market place in an unusual manner — i that Bianchi calls "upside down." Genetic testing previously came from academic labs, and the results would then exist "translated to patient care with the aid of professional society recommendations," she says. Noninvasive tests were instead largely developed by commercial companies. Each lab screens for its own set of autism genes and makes its own decisions about which ones might be relevant. "Information technology'due south similar the Wild West," Wapner says.
Paired with sequencing of whole genomes or at least of the protein-coding portions, these tests would be more powerful. They could detect chromosomal microdeletions linked to autism, for case, which are too small to be picked up past microarray analyses. Merely they might as well produce more incidental and ambiguous results.
"What should we test for? What should we not exam for? Equally our tools get ameliorate, these questions become more important." Ronald Wapner
Consider a 2017 case written report of a 37-year-old woman who opted for a noninvasive test in her 12thursday week of pregnancy. The results were worrisome, suggesting issues on chromosomes 13, 18, 21 and X. Six weeks after, she had an amniocentesis and a microarray assay — to test for fetal chromosomal abnormalities — and both came dorsum normal. To be rubber, though, the lab followed up with whole-genome sequencing of what they presumed to be fetal Deoxyribonucleic acid nerveless during the noninvasive test. They found a 'saw-tooth' blueprint suggestive of cancer. The doctors shifted their concern from her baby to her and brash her to get a body browse, which revealed lesions on her liver. The child turned out to be fine, only the mother was diagnosed with phase-four colon cancer.
"We are increasingly recognizing that the mother is sometimes the source of aberrant Deoxyribonucleic acid patterns," Bianchi says. The DNA obtained for the exam isn't always from the fetus or placenta, but rather from the female parent. Still a pregnant woman almost to undergo a exam is unlikely to exist informed that she might get unwelcome news near her own health. In one survey of more than 300 genetic counselors, fewer than one in 3 regularly warned women of this possibility. And in a written report of Dutch midwives who routinely counsel pregnant women about the tests, only 59 percent correctly answered basic questions about the technology.
Prenatal genetic test results can exist confusing even apart from these sorts of incidental findings. For example, it's difficult to predict during pregnancy the upshot of sure microdeletions on a kid. "Nosotros may find genetic variants which look suspicious," Risch says, simply without seeing the child subsequently on, "we tin't really declare information technology as causal." In other words, the chances of a 'false positive' are higher before birth. For this reason, many labs are more bourgeois in how they report genetic variants plant earlier birth versus later on.
For families that accept older children with autism, Bianchi suggests a safer alternative: Exam the couple and older children earlier turning the spotlight on the fetus. "Yous would focus your prenatal testing for the next child based on what you've found," she says. If the older child has no discernible genetic involvement, it makes no sense to exam the fetus. If the older kid has a clear genetic condition, such as fragile X syndrome, however, it would make sense to test the fetus too.
Ethical challenges:
Given the lack of certainty around prenatal genetic testing for autism — and the intense emotional responses to cryptic results — some couples see little point in information technology, enquiry suggests. Studies too evidence that few couples — only 15.ix per centum in one survey — would terminate a pregnancy if a prenatal examination indicated their child was at risk for a astringent grade of autism. In that same survey, that number was almost 43 percentage for Downwardly syndrome.
Ambiguous results for autism also announced to have limited long-term impact. In a 2018 survey, Wapner and his colleagues establish that parents who received cryptic prenatal testing results rated their babies as less skilled at 12 months onetime than did parents who went home with normal results. Yet that view disappeared by the time the children turned iii — at which point many of the parents said they had started to regret the decision to test in the first identify.
Some parents who desire prenatal autism tests say information technology's because they would similar to be prepared to kickoff interventions as early as possible. Jonathan Green, a child psychiatrist at the University of Manchester in the United kingdom of great britain and northern ireland, has developed a social-communication therapy that parents and clinicians can apply in babies as young as 9 months. He and his team tested the approach in 28 infants who have an older sibling with autism. They first recorded the parents interacting with their infants at home. Then a therapist sat down with the parents to go over the videos and offer feedback. "What nosotros are aiming to do in this treatment is to change the way that the parent is able to read and answer to the kid's communication," Dark-green says. The research is in an early stage, but information technology seems to benefit communication skills in both autistic and typical children, he says.
"We are increasingly recognizing that the mother is sometimes the source of abnormal Deoxyribonucleic acid patterns." Diana Bianchi
Another early on therapy under investigation targets oxytocin — a hormone involved in social bonding. Rat models of autism treated intranasally with oxytocin soon after birth prove fewer autism-like behaviors than untreated rats practise. In that location might even be ways to treat some forms of autism prenatally. In mice, researchers have used the gene-editing tool CRISPR to correct harmful genetic mutations responsible for Angelman syndrome. And dosing pregnant female parent rats with the blood pressure drug bumetanide merely before they go into labor seems to regulate the oxytocin system and mitigate autism traits in their pups.
For now, the most concrete benefit of prenatal genetic testing may only be to help parents better understand the likelihood of autism recurring in some other kid in the family unit — something many are unaware of. The errors in understanding amid parents vary depending on where they live. In i survey in the United States, more than 14 percent of parents who have i autistic child said they thought the adventure of having a second child on the spectrum would be between 75 and 99 percent. In Kingdom of spain, nigh a tertiary of parents said the risk is exactly l-fifty; in Taiwan, where at that place is greater stigma against disabled people, parents put the risk even lower, at almost 33 percentage.
The proportion of parents who make up one's mind non to have more children after one is diagnosed with autism likewise differs past region. In California, roughly i in three makes this decision, according to 1 report. Past contrast, a study in Kingdom of denmark pegged that number at just vi percent. The researchers who led this study betoken out that access to free healthcare in Denmark could make having an autistic kid less of a financial hardship.
Maureen Bennie now says she wouldn't have information technology any other way. Had she known nigh Marc's autism earlier and decided against having more children, it would have been a terrible mistake. "[Marc and Julia] really support each other. I think if I didn't have two of them with autism, information technology would be a much more alone and isolated life for them," she says. Both of her children are doing well equally adults, she adds: "A test will never tell yous how well that child is going to practise in life."
Can You Tell if Your Baby Has Autism Before Birth
Source: https://www.spectrumnews.org/features/deep-dive/the-problems-with-prenatal-testing-for-autism/#:~:text=A%20noninvasive%20test%20for%20Down,including%20some%20related%20to%20autism.