Scientists enhance safety and accuracy in new, non-invasive prenatal

10 March 2012
Scientists enhance safety and accuracy in new, non-invasive prenatal
Down's Syndrome test
A team of scientists, led by Royal College of Pathologists of Australasia (RCPA)
fellow Prof Rossa W. K. Chiu and Prof Dennis Lo, of The Chinese University of Hong
Kong, have developed a revolutionary, non-invasive test for the accurate detection of
Down's Syndrome in unborn babies via the analysis of blood samples from pregnant
Speaking at the RCPA's 11th annual Pathology Update conference at the Sydney
Convention Centre in Darling Harbour today, Prof Chiu introduced the prenatal test,
known as "safeT21," which provides both mothers and children with a higher
standard of safety and accuracy for Down's Syndrome testing.
In 1997, the group discovered that babies release DNA into their mother's blood
plasma during pregnancy. SafeT21 is based on the group's earlier work, and has
proven highly effective in isolating and analysing these trace amounts of DNA, with
an effective diagnosis rate of 99.1%.
A recent large scale study, published in the premier medical journal, BMJ, confirmed
the tests’ accuracy, demonstrating the DNA blood test method provides a high level
of accuracy in diagnosing Down's Syndrome while simultaneously reducing the need
for current invasive prenatal tests by up to 98%.
“Using state-of-the-art DNA sequencing technologies, the new test analyses the DNA
fragments from the mother’s blood to determine if chromosome 21 DNA molecules
are elevated. If they are, it suggests the presence of a Down's Syndrome foetus,”
says Prof Chiu.
The same test was also proven very effective at identifying other chromosomal
abnormalities, for example, trisomy-18 and trisomy-13.
Currently, diagnosing Down's Syndrome involves examining a baby’s chromosomes
obtained through invasive surgical procedures, such as amniocentesis or CVS. Each
of these diagnostic tests carries a small risk to the pregnancy.
“As Down's Syndrome affects about 1 in 800 pregnancies, the discovery of a noninvasive, risk-free test will greatly reduce the number of pregnant couples who are
forced to bear the emotional burden of a potentially risky, daunting and invasive
surgical procedure,” says Prof Chiu.
Dr Narelle Hadlow, of the Western Diagnostic Pathology and Pathwest Laboratory,
Perth, says women need to be aware that receiving an increased risk report for
Down's Syndrome does not necessarily mean they have abnormality in their
"No screening test is 100% accurate. Only further testing can clarify the outcome. All
women taking the test should ensure they are provided with good information, and
possess a strong understanding of the implications of diagnostic tests prior to taking
them," says Dr Hadlow.
SafeT21 became available in Hong Kong, mainland China and the USA last year,
with worldwide distribution to take place over the next twelve months. The test is
available at a present cost of AU$1,000, on par with current invasive methods.
The Royal College of Pathologists of Australasia
The RCPA is the leading organisation representing pathologists in Australasia. Its
mission is to train and support pathologists and to improve the use of pathology
testing to achieve better healthcare.
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