Prenatal genome sequencing expected to pose challenges to doctors
■ The procedure could become common in clinical practice within a decade, experts say. Some express concern that genetic findings may lead to more terminated pregnancies.
By Christine S. Moyer — Posted Aug. 27, 2012
Geneticists soon will be able to identify an unborn child’s risk of developing chronic diseases later in life and possibly shed light on other traits, such as athletic ability and intelligence, medical experts say.
The source of such information probably will be the expectant mother’s blood sample. For the first time, researchers recently extracted fetal DNA from a pregnant woman’s blood and examined the unborn baby’s genome.
The procedure — prenatal whole genome sequencing — is not yet available in the clinical setting. But some health professionals expect that pediatricians and family doctors soon will be sifting through sequencing results of infants and older children.
Key goals of the procedure are improving detection of serious genetic disorders before a child is born and helping create preventive care plans for conditions that young patients are at risk of developing as they age.
“My instinct is this will be available certainly in the next decade, and probably sooner,” said Benjamin E. Berkman, MPH, deputy director of the Bioethics Core at the National Human Genome Research Institute in Bethesda, Md.
But the medical community is not prepared to address the clinical challenges and ethical issues that probably will accompany the procedure, say some bioethicists and geneticists.
Such concerns could include physician uncertainty about which results to give to families and a potential rise in abortions due to parents’ worries about the comprehensive genetic findings, said an article in the July-August issue of The Hastings Center Report, a bioethics journal. Berkman is a senior author of the article.
The report calls for professional medical organizations to begin educating physician members about prenatal whole genome sequencing and how to discuss the procedure with expectant couples. Although the sequencing probably will be ordered by obstetrician-gynecologists, some patients might ask their primary care physicians about the procedure, health professionals say.
The report encourages the medical community to offer guidance on the types of genetic findings physicians should offer expectant parents. It also urges scientists to conduct more research into the kinds of information parents find relevant to reproductive decision-making and how health care systems should accommodate adoption of prenatal whole genome sequencing.
“The tests are here,” said New York geneticist Robert W. Marion, MD. “Technology is going to advance, and the public is going to learn about this. The medical community can’t sit back and wait for this to happen. We have to be very aggressive in getting the word out and training doctors in the significance of this procedure.” Dr. Marion is chief of the divisions of genetics and developmental medicine in the Dept. of Pediatrics at the Children’s Hospital at Montefiore and the Albert Einstein College of Medicine in New York.
Extensive data could cause anxiety
For decades, pregnant women have undergone invasive prenatal genetic testing, such as amniocentesis, to detect specific genetic abnormalities, including cystic fibrosis and Down syndrome. In prenatal whole genome sequencing, however, geneticists will examine the 20,000 to 25,000 genes that make up an individual’s genome. The result will be a dramatic increase in the volume and scope of data available to expectant parents, said The Hastings Center Report.
Although the new pool of data could help families make more informed choices about whether to continue a pregnancy or terminate it, some experts fear that the wealth of information will lead to undue anxiety.
“Families are going to hear there’s a mutation in a gene, and they’re going to terminate pregnancies that are normal simply because they’ve been scared to death,” Dr. Marion said.
Most genetic variations do not affect a person’s health, according to geneticists. There are some, however, that indicate a medical risk. Some of those risks could be related to the genetic susceptibility of developing illnesses much later in life, such as Alzheimer’s disease and cancer.
When developing guidance on prenatal sequencing information to give to families, health professionals should consider whether the illness will affect the person during childhood,Berkman said. An issue that should be discussed is whether doctors will be held liable for not informing families of a genetic variant, which years later contributes to a person’s illness, he said.
“We need to, as a society, think carefully about how to filter this massive amount of information,” he said. “And we need to articulate thoughtful [recommendations] about what findings we should or shouldn’t return to people.”
Dr. Marion is among those concerned about the negative implications of parents learning nonmedical traits of unborn children through prenatal sequencing. Knowing such information could lead parents to terminate a pregnancy if the unborn child has what they consider undesirable traits, he said.
There is not yet official guidance on how to use prenatal whole genome sequencing in the clinical setting. But in May, the American College of Medical Genetics and Genomics approved a policy statement detailing how to integrate whole genome sequencing into practice.
“The transition from traditional targeted gene testing to genomewide analysis constitutes a genuine sea change in medicine, offering vastly enhanced diagnostic power along with unprecedented challenges in test interpretation and reporting,” said college President Wayne Grody, MD, PhD.
The college said sequencing should not be used at this time as an approach to prenatal screening.
The American Medical Association is developing educational resources and point-of-care tools to help doctors implement genomic-based medicine.
“There has to be a tremendous amount of education of health care professionals [on whole genome sequencing] that occurs within the next few years because all of medicine is going to change,” Dr. Marion said.