During Jamie Cassidy's first pregnancy, the fetus developed a genetic mutation so devastating that she and her husband, Brennan, decided to terminate the pregnancy in the second trimester. The next time they try to have a baby, they won't take any chances: They'll use in vitro fertilization (IVF) and screen the embryo's DNA. They wanted to avoid transplanting any embryos with the single-gene mutation that doomed their first pregnancy. Then they began to wonder what other diseases they could save their future son or daughter from.
The Cassidys' doctor introduced them to a genomic prediction company that could assess the likelihood that their children would develop diseases unrelated to a single gene, such as heart disease, diabetes and schizophrenia. The test is no more invasive than screening for a single gene—all the company needs is an embryo biopsy. The science is still in its early stages, but the Cassids don't mind. Brennan has type 1 diabetes, and he doesn't want to pass the disease on to the next generation. "If I could predict that my baby would have a lower chance of developing type 1 diabetes than I do, I would hope so," he told me. "I'd burn all my money to know that."
Thanks to more advanced genetic testing technology, in vitro fertilization (IVF)—an expensive, invasive treatment originally developed to help people with fertility problems—is becoming a tool for optimizing health. A handful of companies offer screening for diseases and conditions ranging from life-threatening (cancer) to life-changing (celiac disease). In many cases, the genetic link to these diseases is poorly understood or tenuous and is just one of many factors that determine whether a person develops a particular disease. But bringing another human into the universe can be a scary enough prospect that some parents are turning to extensive genetic testing to help select future offspring.
Genetic screening has been an important component of IVF and pregnancy for decades. Medical guidelines recommend that any aspiring mother should have the option of testing her own DNA to see if she is at risk of passing on dangerous genes, a practice known as carrier screening. If both parents carry a specific mutation, your doctor may recommend in vitro fertilization and embryo screening. Traditionally, these measures have been limited to diseases associated with single gene mutations, such as Huntington's disease, most of which are extremely rare and severely impact children's quality of life. During IVF, embryos are also typically screened for chromosomal abnormalities to help avoid miscarriage, as well as general non-genetic conditions such as Down syndrome.
As scientific understanding of the genome continues to advance, companies including Genomic Prediction and rival Orchid have begun offering a test that promises a more comprehensive investigation of risks lurking in an embryo's genes using a so-called polygenic risk score. Most common diseases are not related to a single gene; a polygenic risk score is designed to predict the likelihood of developing a disease such as diabetes over a lifetime, where many genes contribute to a person's risk. Consumer DNA testing companies like 23andMe use these scores to tell customers whether they have a slightly above-average likelihood of developing celiac disease, with the disclaimer that lifestyle and other factors also affect their chances. In theory, these risk scores could help identify clients who need colonoscopies earlier in life or who need to double down on their New Year's resolution to eat healthier. But the current scientific consensus is that polygenic risk scores do not yet provide useful insights into a person's health, even if they do.
Analyzing an embryo's DNA to predict its risk of developing complex genetic diseases such as diabetes is a trickier problem. These tests, which can cost thousands of dollars and are often not covered by insurance, involve sending a small sample of embryos to the company's lab. In the United States, such tests do not require FDA approval. Genomic predictions can even provide clients with an assessment of the “healthiest” embryo overall. But the control these services offer is an illusion, like the promise of predicting the weather a year in advance, says Robert Klitzman, a Columbia University bioethicist and author of the book designer baby,tell me. A spokesman for the American Society for Reproductive Medicine told me there isn't enough high-quality data to tell whether such tests are useful. Last year, the American College of Medical Genetics and Genomics issued a lengthy position statement concluding that the benefits of screening embryos for polygenic risk are "unproven" and that the tests "should not be provided as a clinical service." . The statement raises the possibility that people may undergo additional, unnecessary IVF in search of healthier embryos.
go through Robert Krizman
Genomic Prediction published a rebuttal to ACMG, citing several studies led by company researchers that concluded that among siblings, those with lower risk scores were significantly more likely to develop a specific disease. Small. But the fact is that screening embryos for polygenic risk is not as effective until the embryos selected to develop into fetuses are born, grow up, develop diabetes or not develop diabetes. Both Genomic Prediction and Orchid tell me that humans shouldn't have to wait that long to get the insights their tests provide. Noor Siddiqui, founder and CEO of Orchid, told me that polygenic risk scores are “one of the most valuable pieces of information you can get.” Nathan Treff, chief scientific officer at Genomic Prediction, is similarly optimistic. "Everyone has some kind of family history of diabetes, cancer and heart disease. So we really don't have a situation where there's no reason to test," he told me.
Many of the experts I spoke to about these tests worry that people might choose IVF because they're seeking a level of certainty that companies can't truly promise. A study last year found that Americans showed strong interest and approval in screening embryos for polygenic risks. Currently, most of the clients I interview are using advanced testing that includes polygenic risk because they were undergoing IVF anyway. Many genomic prediction customers who use these scores are participants in clinical trials. But Tara Harandi-Zadeh, an investor in Orchid, told me that even though she and her husband have no history of fertility problems or genetics, she still plans to undergo IVF. Harandi-Zadeh is particularly concerned about de novo mutations—genetic changes that occur spontaneously without any genetic link. She wants to screen her embryos for single-gene disorders and plan for the risk of polygenic disorders. "If I had this information, I could help my child get treatment or check-ups at various stages of life, or just be prepared for it," she said. Trev told me that people like Harandi-Zadeh only They represent a small portion of Genomic Prediction's customers, but their numbers are growing.
Scientists don't know enough about the genome to confidently predict what any individual embryo would look like if it went on to develop into a human. Most genes influence many aspects of our lives—our health, our physical characteristics, our personality—but only a small subset of these interactions have been studied. "You don't know the full package," Klitzman said. "Bipolar disorder is associated with creativity. So if you screen for bipolar disorder, you may also screen for creativity genes." Since no embryo is completely risk-free, future parents may also have to decide whether they think the risk of diabetes or the risk of heart disease sounds worse. A paper published last week put it this way: "Even if clinical, ethical and social issues are ignored, the expected reductions in disease risk are limited at best."
These concerns are important. More and more people have turned to IVF for reasons other than infertility. Some people choose their children based on their gender. Jeffrey Steinberg, a fertility doctor with clinics in the United States and internationally who offers eye color selection services, told me he was looking into height. Orchid assesses genetic risks for some autism spectrum disorders, and Genomic Prediction plans to add similar screenings to its catalog. A paper published last week argued that editing embryos - rather than just testing them - could mitigate genetic risks for a variety of diseases, while acknowledging that it could "deepen health inequalities". (In the United States, clinical trials of embryo editing cannot be approved by the FDA, and public funds cannot be used for embryo editing research.) Critics say that even if the technology can reduce the prevalence of diseases such as diabetes, doing so may also reduce the prevalence of diabetes. prevalence of other diseases. Reinforcing discrimination against those born with such “undesirable” traits. Social services and support for people with these conditions may also be undermined - similar concerns have been raised in Iceland, for example, where pregnancy screening has all but eliminated births with Down syndrome.
Even if science does catch up with the ambitions of companies like Genomic Prediction, genetics will never guarantee a child a healthy life. “Of the 100 problems your baby could have, 90 percent or more are not genetic,” Hank Greeley, director of the Center for Law and the Biosciences at Stanford University, told me. That's part of the reason why the Cassidys decided to ignore most of the screening results and simply select embryos that didn't have the single-gene mutation Jamie carried and were at the lowest risk of developing diabetes. "We didn't want to have a 6-foot-2 kid with blond hair and blue eyes and go to Harvard. We just wanted a healthy baby," Brennan told me.
Their son was born in 2023. So far, his development indicators are in the leading position: he is big and tall; he talks and walks early. It may be years before they know whether he has diabetes. But they say it's hard not to feel like they've chosen the right embryo.
When you purchase books using links on this page, we receive a commission. thank you for your support Atlantic.