Tag: amniocentesis

Bioethics News

Clinical efficiency and pregnancy screening

UK researchers are hailing the development of a “safer” and more “cost-effective” disability-screening test for pregnant women. 

The newly developed test, which involves screening the blood of a mother for foetal DNA, is a far less invasive alternative to the current procedure (amniocentesis) used to detect Down’s syndrome.

The new method was recently trialled on 2500 expectant mothers at Grand Ormond Street Hospital in London, and researchers say it is both less risky and cheaper.  

The current method, amniocentesis, involves the sampling of amniotic fluid obtained through the insertion of a hollow needle into a mother’s uterus. This procedure significantly increases the chance of a miscarriage, aside from being quite frightening and often painful for pregnant women.

The new procedure involves one simple blood test.

“Instead of taking an invasive sample, we can take a sample of the mother’s blood, and we can look at the levels of DNA in mum’s blood and, if there’s a little bit more chromosome 21 than we expect, that will be an indication that he baby has Down’s syndrome”, explained Lucy Jenkins, director of Genetics at Great Ormand Street Hospital.

The test does not, however, totally eliminate the need for amniocentesis. Mothers who ‘test positive’ on the blood test still need to undergo amniocentesis for confirmation.

“We have approached women to be involved in this study who maybe have a more moderate risk associated with Down’s syndrome, so there are women having access to the test who wouldn’t previously have had,” Dr. Jenkins said.

“Also, women who would never consider having an invasive test, maybe would access this test because it’s less invasive.”

The views, opinions and positions expressed by these authors and blogs are theirs and do not necessarily represent that of the Bioethics Research Library and Kennedy Institute of Ethics or Georgetown University.

Bioethics Blogs

Do we really need an even better prenatal test for Down syndrome?

Chris Kaposy challenges the need for further developments in prenatal testing for Down syndrome.

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The journal Clinical Proteomics recently published an article describing a new experimental prenatal test for Down syndrome that uses only a maternal urine sample. The test has been touted in the media as providing instant results with 90% accuracy. The promise of such a test – if it ever comes to market – is that women could administer it at home, early in pregnancy, with low cost.

Prenatal testing for Down syndrome and other aneuploidies is a rapidly advancing field. In the past few years, biotech companies have developed prenatal Down syndrome tests that detect cell-free fetal DNA in the pregnant woman’s blood. These tests have been dubbed “non-invasive prenatal tests” because they provide highly accurate results without having to resort to invasive tests such as amniocentesis or chorionic villus sampling, which carry a risk of miscarriage. The new urine test for Down syndrome, developed by the biotech firm MAP Diagnostics Ltd., is the latest advance in a “corporate arms race” to develop prenatal tests for Down syndrome that are accurate and less invasive, cheaper, easier to administer, and that can be administered earlier in pregnancy than previous methods of testing.

A majority of the time, a prenatal diagnosis of Down syndrome leads to a selective termination of the pregnancy. As I have argued elsewhere, because of their ease of use and their non-invasiveness, the new non-invasive prenatal tests for Down syndrome could contribute to increased numbers of selective terminations of pregnancy.

The views, opinions and positions expressed by these authors and blogs are theirs and do not necessarily represent that of the Bioethics Research Library and Kennedy Institute of Ethics or Georgetown University.

Bioethics Blogs

FDA Regulation and Early Prenatal Testing

Editors’ note: The US Food and Drug Administration is currently considering regulation of laboratory developed tests (LDTs), which include noninvasive prenatal tests. The comment here was submitted to the FDA by George Estreich, as part of a comment period that closed on February 2. The FDA’s materials on LDTs can be found here.

To the Food and Drug Administration:

I’m writing to urge the FDA to regulate the new, noninvasive prenatal tests, and I wish to focus particularly on health claims being made in the advertising for the tests. If prenatal testing is to be of greatest benefit both to individual women and to society at large, the information that accompanies that testing should be accurate, complete, useful, and most of all nondirective. The ads for NIPT do not meet these criteria. As a result, the advertising has a number of potential adverse consequences for consumers.

Beth Daley’s recent investigative report in the Boston Globe offers a disturbing look at the consequences of misinformation: as Daley notes, when both health professionals and patients believe that the test is “99% accurate,” as it is often advertised to be, both false positives and false negatives have serious consequences for prospective parents’ state of mind, and for the course of an intended pregnancy. Believing the test to be accurate, women have aborted healthy fetuses in the case of a false positive, or have carried fetuses with severe conditions to term.

These beliefs are mistaken, but they are completely understandable, given the expertly executed ads for the technology. Though the figure “99%” is ubiquitous in the ads, whether referring to sensitivity, specificity, or “accuracy,” the number of true interest to a consumer—the positive predictive value—is either in fine print, or difficult to find.

The views, opinions and positions expressed by these authors and blogs are theirs and do not necessarily represent that of the Bioethics Research Library and Kennedy Institute of Ethics or Georgetown University.

Bioethics Blogs

Prenatal Tests: Oversold and Misunderstood

Lincoln Samuel tested positive for Edwards syndrome, but was born perfectly healthy

On Sunday of this week, the Boston Globe published an article that I’ve been waiting to see for months. It’s Beth Daley’s investigative report on noninvasive prenatal testing, and I’m hoping it will both create a larger public conversation, and shift the terms of the conversation so far.

As many of you know, NIPT is a new technology that promises to detect Down syndrome and other chromosomal conditions based on a maternal blood draw alone. These tests are sold as “99% accurate” something I believed for a long time, and that some health professionals seem to believe but as genetic counselor Katie Stoll has written, the actual test performance is nowhere near as good. NIPT is not diagnostic; it is a screening test, and a “positive” result only means that a diagnostic procedure, like amniocentesis or CVS, will be required to confirm fetal status. 

I believe that it is not enough to consider reproductive technologies in the abstract. They cannot be contemplated only in a statistical or bioethical vacuum: we need fact-based stories to perceive human consequences on the ground. Beth’s article accomplishes this by focusing on the cost of false positives and false negatives in real people. She also delves into the facts about LDTs, or laboratory-developed tests, which are currently unregulated by the FDA. Because her article has already sparked pieces at The New York Times, NBC News, and elsewhere, I have hopes that a new conversation is beginning.

The views, opinions and positions expressed by these authors and blogs are theirs and do not necessarily represent that of the Bioethics Research Library and Kennedy Institute of Ethics or Georgetown University.

Bioethics Blogs

Genetic Testing For All: Is It Eugenics?

In recent weeks, there’s been talk of three types of genetic testing transitioning from targeted populations to the general public: carrier screens for recessive diseases, tests for BRCA mutations, and non-invasive prenatal testing (NIPT) to spot extra chromosomes in fetuses from DNA in the maternal bloodstream.

Are these efforts the leading edge of a new eugenics movement? It might appear that way, but I think not.

When I began providing genetic counseling 30 years ago at CareNet, a large ob/gyn practice in Schenectady, NY, few patients were candidates for testing: pregnant women of “advanced maternal age” (35+), someone with a family history of a single-gene disorder or whose ethnic background was associated with higher prevalence of a specific inherited disease. Their risks justified the cost and potential dangers of the tests.

Now the picture is rapidly changing as plummeting DNA sequencing costs and improved technologies are removing economics from the equation. It’s becoming feasible to test anyone for anything – a move towards “pan-ethnic” genetic screening that counters the “sickle-cell-is-for-blacks and cystic-fibrosis-is-for-whites” mindset.

So here’s a look at three very different types of genetic tests that are poised to make the leap to the general population. And despite new targets revealed with annotation of human genomes, some of the detection technologies themselves are decades old.

#1: CARRIER SCREENING

Population screening for carriers of single-gene diseases has been around since those for sickle cell disease and Tay-Sachs disease in the early 1970s. We learned a lot from their starkly different results. For years, labs such as Athena Diagnostics, the Baylor College of Medicine Medical Genetics Laboratories, Emory Genetics Laboratory, Ambry Genetics, GeneDx and others have added genetic tests to their rosters, which now cover hundreds of single-gene diseases, from A (Alport syndrome) to Z (Zellweger syndrome).

The views, opinions and positions expressed by these authors and blogs are theirs and do not necessarily represent that of the Bioethics Research Library and Kennedy Institute of Ethics or Georgetown University.