Safer prenatal blood test found for Down syndrome

WASHINGTON : A prenatal blood test can be used to determine if an unborn baby has Down syndrome without the small risk to the foetus posed by invasive testing methods such as amniocentesis, US researchers said yesterday.

Researchers led by Stephen Quake of Stanford University in California created a way to look for the extra chromosomes that cause Down syndrome and similar birth detects in the tiny amounts of foetal DNA that circulate in the mother's blood.

The test, which requires a small blood sample from the mother, is safer than amniocentesis, in which a needle is inserted into the uterus, and can be done earlier in a pregnancy.

Down syndrome, which causes mental retardation and other problems, is caused when a child has three copies instead of the normal two of chromosome 21. The test also detects other chromosomal conditions such as Edward syndrome, which kills half of babies in the first week of life and Patau syndrome, which kills more than 80 per cent of children in infancy.

Mr Quake's team demonstrated the accuracy of the new genetic test in a small study involving 18 women. It accurately identified the nine women with a Down syndrome pregnancy and three others with foetuses with different chromosomal disorders, according to the journal Proceedings of the National Academy of Sciences.

"It's the first universal, noninvasive test for Downs syndrome. So this should be the first step in putting an end to invasive testing procedures like amniocentesis and chorionic villus sampling, Mr Quake said. - (Reuters)

© 2008 The Irish Times

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