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New genetic screen for Down syndrome to reduce risks of invasive tests

Media release

Curtin University researchers have found a new non-invasive test for Down syndrome could increase detection rates and significantly reduce the need for invasive diagnostic procedures, which can cause miscarriages.

Professor Peter O’Leary, Deputy Director at Curtin’s Centre for Population Health Research, said Down syndrome was the most common chromosome abnormality in humans.

“Expectant mothers are offered a screening test in their first trimester to estimate the risk of their fetus having Down syndrome. Those found to have a high risk are offered diagnostic testing,” Professor O’Leary said.

“The current diagnostic tests, such as amniocentesis, are invasive and carry a small risk of miscarriage.

“Our study sought to analyse how cost-effective it would be to include a new non-invasive prenatal test as a second-tier test to provide a more accurate risk estimate, prior to offering invasive testing.”

The study reviewed 32,478 single baby pregnancies screened between January 2005 and December 2006 in Western Australia and found by including the new non-invasive test, the number of invasive diagnostic procedures and procedure-related miscarriages would have been reduced in high-risk women by 88 per cent.

“Currently, 75 per cent of women choose to have invasive diagnostic testing following a high-risk result,” Professor O’Leary said.

“Our study found that if all pregnant women identified as high-risk, adopted this non-invasive testing method, up to seven additional cases of the genetic disorder could be confirmed during pregnancy over two years.

“We also found that implementing this new testing method would increase the cost of prenatal screening for Down syndrome to the public health system by less than 10 per cent.”

The new, non-invasive test is currently available only in the private health sector in Australia.

The study titled Prenatal screening for Down syndrome in Australia: Costs and benefits of current and novel screening strategies is available online at http://onlinelibrary.wiley.com/doi/10.1111/ajo.12117/pdf or http://www.ncbi.nlm.nih.gov/pubmed/24090461.

Notes to the Editor

Down syndrome occurs in one in every 350 pregnancies in Western Australia. It occurs at conception, affects all ethnic and social groups and there is no cure.

Down syndrome is caused by a third copy of chromosome 21.

More information about prenatal screening can be found at http://www.genomics.health.wa.gov.au/publications/docs/DOH-policy-recommendatinos-2010-15.pdf