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Non-invasive Down’s syndrome tests make progress

Posted in Diagnostic testing, Scientific research, Screening by Matt at WelcometoIllinois on January 29, 2009

Genetic analysis company Sequenom has announced that it is making progress towards commercialising its non-invasive test for Down’s syndrome and other chromosomal abnormalities.

Based on an expanded sample of 858 tests “the Sequenom SEQureDx RNA-based technology demonstrated a 100% positive predictive value (PPV) and a 99.9% negative predictive value (NPV).”

As The Street notes, that last figure indicates that the company is no longer able to repeat its
previous claim to no false positives.

“Until today, Sequenom’s test had a 100% detection rate for Down syndrome and a 0% false positive rate when used in just under 400 pregnant women — a perfect record. While Wednesday’s disclosure of one false positive test in more than 858 total samples mars that flawless performance, Sequenom CEO Harry Stylli says an overall false positive rate of one-tenth of 1% is significantly better than current prenatal screening methods for Down syndrome, which can have a false positive rate of around 5%.”

UPDATE – It turns out the test results were wrong – UPDATE

According to The Street, the test works like this:

“The Sequenom test relies on new technology that can detect minute amounts of fetal RNA in a mother’s bloodstream. Using a small sample of blood taken from the mother, Sequenom isolates fetal RNA [ribonucleic acid] and determines whether there are two copies of chromosome 21 (a healthy baby) or an extra copy of the chromosome, which would indicate Down syndrome.”

Sequenom is coming to make its test available in the US in June, although as Xconomy reports “The medical audience will demand evidence published in peer-reviewed journals, and loads of it, before they give their full stamp of approval.”

Detailed results should be published in peer-reviewed journal in mid-2009, according to the company. Recommendation from American College of Obstetricians and Gynecologists will likely not come until 2010 or 2011, at the earliest.

Sequenom is not the only company developing new non-invasive testing techniques. I previously wrote about similar testing technology under development at Stanford University being licensed to a company called Fluidigm.

A company called Artemis Health has also acquired a license from Stanford University to develop cell-free fetal DNA prenatal diagnostic tests.

Meanwhile a company called Lenetix announced that it is making progress with maternal serum test developed at the University of Vermont that make use of methylation-sensitive amplification (MSA) of fetal nucleic acid markers.


2 Responses

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  1. […] previously statedit had achieved 100% accuracy on positive results and 99.9% on negative results. It now claims 96.6% […]

  2. […] about DNA testing for prenatal diagnosis of Down’s syndrome before. In particular Sequenom appeared to making good progress but has subsequently admitted that the data was mishandled by […]

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