Written by Brian Skotko, MD, MPP
Children’s Hospital Boston Clinical Genetics Fellow, Down Syndrome Program
Last week a breaking study in the British Medical Journal offered a glimpse into our reproductive futures: soon, a non-invasive test will allow expectant mothers to know whether their fetus has Down syndrome.
Current prenatal tests for Down syndrome are invasive and can potentially cause a miscarriage, making them undesirable for many women. But now scientists have learned how to quantify the fetal copies of the 21st chromosome, the genetic basis for Down syndrome, with a simple blood test taken in the first trimester. These tests would be safer, faster, and, most likely, cheaper than anything available today.
While the research brings a scientific breakthrough, the prenatal tests also usher in a provocative question: will the births of babies with Down syndrome begin to decrease because of this testing? Since the new tests are non-invasive, researchers believe that the overwhelming majority of expectant parents will pursue such testing. And, with the tests being safer and cheaper than current methods, insurance companies will most likely have no problem defraying costs for anyone who wants one. As a result Down syndrome will most likely become a prenatal discovery for nearly all pregnant women. And, when prenatal testing does confirm that the child will be born with Down syndrome, more expectant parents will need to decide: should we continue or terminate our pregnancy?
Part of their decision will be based on the information they receive about Down syndrome from their medical providers. Yet, the majority of medical students argue that they get minimal education on children with intellectual disabilities; and nearly half of obstetric fellows claim their residency training is “barely adequate” to “nonexistent” in terms of how to counsel would-be parents of a child with intellectual disabilities. Some physicians who do routinely deliver a prenatal diagnosis also admit to purposely describing Down syndrome in negative terms. Not unexpectedly, then, many mothers feel that they receive inadequate, incomplete and sometimes offensive information about children with this condition.
Currently, 92% of all women worldwide who receive a definitive prenatal diagnosis of Down syndrome choose to terminate their pregnancy. Based on those numbers, what does the future hold for the Down syndrome population once the new prenatal tests are available? The answer lies nestled in profoundly personal decisions, but still raises an important question, one that will be asked more and more frequently as other forms of prenatal testing come to the market: which forms of human genetic variation are valuable, and which are not?
These will be private and difficult decisions for parents to make, but at what point should our professional organizations weigh in? Should expectant parents be able to select out fetuses based on the sex alone? Should an expectant mother be allowed to test her fetus for an adult-onset condition, like breast cancer? If genes are one day identified that shape a person’s sexual orientation, do parents have the right to know that information prenatally? The questions are endless, but the time is ripe for us to discuss them. Let’s begin those conversations now, before the tests force us to do so.