Houston Chronicle Examines Prenatal Genetic Test That Can Detect More Than 200 Conditions

Main Category: Genetics
Also Included In: Pregnancy / Obstetrics
Article Date: 24 Dec 2008 - 3:00 PDT

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The Houston Chronicle on Sunday examined the debate surrounding a new prenatal DNA test that screens fetuses for hundreds of genetic abnormalities, including disorders undetectable with previous tests. The screening, which is being promoted by a laboratory at Baylor College of Medicine, involves a more sophisticated analysis of fetal cells taken from a pregnant woman's uterus for standard chromosomal testing. The test uses a computer chip to analyze the fetal cells for defective components of the patient's genetic material. The test can detect more than 200 genetic syndromes, including conditions not detected by standard genetic analysis and conditions that do not appear until after birth. The screening does not target conditions that can be treated in the womb or after birth, the Chronicle reports. The test also is available commercially at Emory University and at a private laboratory in Spokane, Wash., the Chronicle reports. In addition, Baylor currently is participating in a multi-institutional study with Emory and Columbia University that is evaluating the test in 4,000 pregnancies. Arthur Beaudet, chair of molecular and human genetics at Baylor, said the test is "the beginning of a sea change in prenatal diagnosis," adding that he believes "it will replace current prenatal screening within five years, becoming the new test of choice for couples seeking the maximum information about their developing fetus."

The Chronicle reports that the availability of the test has led to an ethical debate over whether its accuracy has been sufficiently established, whether it should be regulated by FDA and "whether such screening reflects a trend toward eugenics." Supporters of the test say it can allow parents to prepare for raising a disabled child or give parents peace of mind if the results come back negative. The test also can allow couples to decide to terminate a pregnancy if they believe that raising a severely disabled child would cause them severe emotional and financial stress. William Winslade, bioethicist at the University of Texas Medical Branch at Galveston, said, "As long as the information is reliable, a pregnant woman has a right to know as much as possible about the kind of parenting she'd face." He added that a woman who undergoes the screening might decide "that she isn't up to the challenge of caring for a handicapped child or that she doesn't want to increase suffering in the world." However, Mary Mahowald, a University of Chicago ethicist, said the new test has "troublesome implications" because it "suggest[s] an attitude that deems the lives of people with disabilities not worth living." Mahowald added that the testing most likely will be used by the most affluent couples, which could lead to a disproportionate number of disabled people born to lower-income families. The screening costs $1,600, but insurance typically covers a portion of the charge, according to Beaudet. He added that demand for the test has been minimal and that his lab performs two to four tests per week, totaling about 500 tests since 2005.

Critics have called for increased regulation of genetic testing by FDA. A December 2005 editorial in Nature on the Baylor test said that "children may be born with unexpected disease or fetuses may be terminated on the basis of false information. Let's hope that such episodes don't have to be documented before the FDA acts." Critics also have questioned the reliability of the test and raised concerns that inaccurate diagnostic information could cause "undue worry" for parents or lead them to abort a healthy fetus, the Chronicle reports. These critics argue that the ongoing multi-institutional study should be completed before the test is offered commercially. However, Beaudet said the vast majority of screenings produce clear-cut diagnostic results, with ambiguous test results occurring about 1% of the time. According to a study published last month in Prenatal Diagnosis, out of 300 tests, the screening found 15 cases of clear-cut abnormalities and three ambiguous results. Five of the couples who received a diagnosis of abnormalities decided to abort the fetus, but none of the couples receiving the "uncertain" diagnosis did so, the study found. Beaudet added that couples who use the screening service also are offered genetic counseling. However, some advocates have expressed concern about the quality of counseling offered and whether counseling would be available from private, non-academic labs. Bioethicist Arthur Caplan of the University of Pennsylvania said, "[W]hat kind of counseling? I think people undergoing this testing need to hear from people who've raised kids with these kids of issues, or the disabled themselves" (Ackerman, Houston Chronicle, 12/21).

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