To Your Health: NLM update Transcript

Are genetic tests more precise than standard screening?: 05/26/2015

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Greetings from the National Library of Medicine and MedlinePlus.gov

Regards to all our listeners!

I'm Rob Logan, Ph.D., senior staff, U.S. National Library of Medicine (NLM).

Here is what's new this week in To Your Health, a consumer health oriented podcast from NLM, that helps you use MedlinePlus to follow up on weekly topics.

A genetic test is more clinically precise than standard screening for Down's syndrome and two other types of trisomy among pregnant women, finds a rare, comparative study recently published in New England Journal of Medicine.

Trisomy is when a person has three copies of a chromosome instead of two.

The study finds the ability to detect Down's syndrome (also known as trisomy 21) is significantly higher using genetic (cell free DNA) testing compared to standard screening.

In addition, the false positive rates for Down's syndrome and two other forms of trisomy were significantly lower in the group that received genetic testing compared to a standard screening group. In addition to Down's syndrome, the authors compared screening for trisomy 13 (Patau syndrome) and trisomy 18 (Edward's syndrome).

The study's 13 authors write (and we quote): 'In this large, routine prenatal-screening population, (cell free DNA) testing for trisomy 21 (Down's Syndrome) had higher sensitivity, a lower false positive rate, and higher positive predictive value than did standard screening...' (end of quote)

The study compared 15,841 women who were tested in the first trimester (10-14 weeks) of their pregnancy at 35 international medical centers. The women were randomly assigned into groups who received a noninvasive cell free DNA test or a noninvasive standard screening test used in many medical centers.

The study's authors explain while cell free DNA testing was introduced in 2011, the current study may be the first to test its efficacy compared to a traditional multiple marker screening .

While the authors explain the findings suggest cell free DNA testing is superior to screen for Down's, Patau and Edward's syndrome, the current research did not compare differences in costs between genetic and standard screening procedures. The authors note the study's findings suggest future cost utility comparative studies are warranted.

Meanwhile, a link to insightful screening information for Down's syndrome (from Up-to-Date) is provided in the 'prevention/screening' section of MedlinePlus.gov's Down's syndrome health topic page. MedlinePlus.gov's Down's syndrome health topic page provides an overview of Down's syndrome (from the American Academy of Family Physicians) in the 'overviews' section.

A link to more comprehensive information about Down's syndrome (from NLM's Genetics Home Reference) is available in the 'genetics' section of MedlinePlus.gov's Down's syndrome health topic page. Genetics Home Reference also contains comprehensive information about Patau and Edward's syndrome -- and can be accessed directly by typing 'Genetics Home Reference' in any Internet search engine.

MedlinePlus.gov's Down's syndrome health topic page additionally provides links to the latest pertinent journal research articles, which are available in the 'journal articles' section. Links to clinical trials that may be occurring in your area are available in the 'clinical trials' section. You can sign up to receive updates about Down's syndrome as they become available on MedlinePlus.gov.

To find MedlinePlus.gov's Down's syndrome health topic page type 'Down's syndrome' in the search box on MedlinePlus.gov's home page, then, click on 'Down's syndrome (National Library of Medicine).'

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