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Quick test detects foetal abnormality in hours

20 June 2012

Amniocentesis to draw out cells in the amniotic fluid for testing

Normal foetus with two chromosome 21 (pink) Foetus with an extra chromosome 21, a sign of Down's syndrome
The NUS Yong Loo Lin School of Medicine has come up with the world's fastest test to find out whether an unborn baby has Down's syndrome or other genetic abnormality.

Dubbed FlashFish, the diagnostics shows whether such defects are present within hours, compared to the next-fastest tests AmnioPCR and AmnioFish which need two to three days for the results.

Doctors recommend amniocentesis for expecting women who are 35 years and above, or those with high-risk pregnancies. The procedure draws out cells from the amniotic fluid to examine the chromosomes in the cell nuclei to determine if the foetus has any genetic defect. A complete analysis can take up to 14 days.

Lead researcher Assoc Prof Mahesh Choolani from the Department of Obstetrics and Gynaecology said that the new test focuses on chromosomes of interest, namely 13, 18, 21, X and Y which are frequently involved in foetal abnormality. For instance, an additional chromosome 21 results in Down's syndrome, while a missing X chromosome causes Turner syndrome where a girl experiences developmental problems.

The investigators improved the fluorescence in situ hybridisation (FISH) screening using two different types of probes. They managed to speed up the results such that an amniotic sample collected in the morning can have its results by 6pm. Prof Choolani noted that the same-day data shortens the anxious wait and greatly alleviates a patient's worry whether there is problem with her baby.

Prof Choolani disclosed that two studies on 140 samples from pregnant women in Singapore have shown 100 per cent accuracy.

The team has patented the technology, which was first offered at National University Hospital. It is now also available at other hospitals and clinics, costing from S$450 to $482.

The breakthrough method was presented at the recent inaugural University Obstetrics and Gynaecology Congress organised by NUS, which attracted more than 400 participants from around the world.