The Philadelphia Inquirer featured Clinical Supervisor Barbara Bernhardt of Arcadia University’s Genetic Counseling graduate program in a front page article, “Seeing a fetus’ future ills,” on Nov. 20. The story discusses recent genetics findings that “could expand prenatal testing while reducing the number of babies born with serious defects.” However, Inquirer staff writer Marie McCullough reports that many DNA variants are not yet understood.
In February, the results of a national validation study of more than 4,000 fetal DNA samples confirmed that microarray sensitivity surpasses karyotyping. Microarrays identified all 371 abnormalities found by karyotyping – and many that the conventional test missed.
Of fetal samples from older women, about 2 percent had a flaw not found with the older technology. Of DNA from fetuses with physical defects seen on ultrasound, about 6 percent had genetic errors revealed by microarrays but not karyotyping.
Study leader Ronald Wapner, a maternal-fetal medicine specialist at Columbia University, declined an interview pending publication of the full study. But in a February news release, he said: “Why would anyone want to continue to use the standard method, which gives only part of the answer?”
Anyone with a choice probably would not want to, judging from the Penn study, led by genetic counselor Barbara A. Bernhardt. It interviewed 23 women who got abnormal microarray results in the national study.
All 23 originally agreed to the newer test because they could “get more information about their baby’s health at no additional cost or risk,” Bernhardt wrote.
Some, however, later regretted their decision. Those who got a normal karyotype followed by an abnormal microarray felt blindsided, despite having been counseled that it could happen.
Worse, about 1.6 percent of women with conflicting test results in the national study were told that the microarray finding was of “potential” but “uncertain clinical significance.”
This information – Bernhardt called it “toxic knowledge” – led to anxiety, confusion, frustration, depression, and, in some cases, abortion. Eight women who opted to give birth admitted to ongoing worries, even after the baby appeared normal.
“The public expects that more certainty will accompany more technology,” Bernhardt said. “But the opposite is true, particularly in genetics.”