April 19, 2012

Ramifications of prenatal Down syndrome test debated

Ramifications of prenatal Down syndrome test debated

The non-invasive test became available late last year, but the advancement in genetic screening for the chromosomal anomaly that causes Down syndrome has been met with strong reactions.

Researchers from the departments of Obstetrics, Special Education and Pediatrics joined parent advocates last week for a provocative discussion on the possible implications of this new prenatal test at a Vanderbilt Kennedy Center-sponsored event.

Noninvasive prenatal testing (NIPT) is offered at Vanderbilt University Medical Center and nationwide and has demonstrated high accuracy (99.1 percent) for detecting fetal trisomy 21 or Down syndrome.

The greatest advantage to this test — the non-invasiveness — is also the greatest disadvantage, says Martha Dudek, M.S., LCGC, genetic counselor, senior associate in Obstetrics and Gynecology and associate in Pediatrics.

“By removing the barrier of risk, there is concern that patients will not take the time to pause and ask themselves ‘do I really want this information at this time in my pregnancy?’”

Dudek says the test is intended for expectant mothers at high risk for a baby with a chromosomal abnormality.

“The hope is that women can be reassured very early in their pregnancy and go on and enjoy their pregnancy without that worry and concern of Down syndrome despite advanced maternal age, an abnormal screening, a finding on an ultrasound or family history,” Dudek said.

The point at which the test can be administered — as early as 10 weeks gestation — is what has parent advocates like Christine Sartain concerned that more of these pregnancies will be terminated.

“If you are not considering ending the pregnancy, what is the true benefit of knowing?” said Sartain. “It all boils down to the value that is placed on our children with Down syndrome. We just want our kids to be valued.”

Frank Boehm, M.D., professor of Obstetrics and Gynecology and associate professor of Radiology and Radiological Sciences, says with regards to ethics, this is not a new subject.

“This [test] is just the new kid on the block, and the new kid is always going to change,” Boehm said.

Boehm predicts this part of the country will see a stable population of patients with Down syndrome and does not consider termination of pregnancies as significant of an issue in this region.

“One of the things I love about practicing in Nashville is that it is a very religious community,” Boehm said. “Most of our patients come to us with the attitude of ‘whatever I have is what I’m going to take home with me.’”

In addition to Down syndrome, NIPT can now detect trisomy 13 and 18, genetic disorders that include a combination of birth defects and a mortality rate of approximately 90 percent by age 1.

Robert Hodapp, Ph.D., professor of Special Education and director of Research for the VKC University Center for Excellence in Developmental Disabilities (UCEDD), moderated the event, which was part of the Research Ethics Grand Rounds, a series sponsored by the Vanderbilt Kennedy Center to inform the university community about ethics related to conducting research, particularly issues involving individuals with disabilities.