Research reveals new ways to test for Downs

Howard Hughes Medical Institute researchers have developed a new prenatal blood test that accurately detected Down syndrome and two other serious chromosomal defects in a small study of 18 pregnant women. If confirmed in larger trials, they say, the test would offer a safer and faster alternative to invasive prenatal tests such as amniocentesis that pose a small risk of miscarriage.

Researchers have long known that a pregnant woman's blood contains small amounts of DNA from the fetus. Howard Hughes Medical Institute researcher Stephen R. Quake and colleagues at Stanford University devised an ingenious way to the scan fetal DNA present in the mother's blood to determine whether the fetus' cells contain extra chromosomes associated with several types of severe birth detects.

At present a procedure called amniocentesis is used to test for chromosomal abnormalities. This involves inserting a long needle through the mothers abdomen and drawing off fluid from the womb. As well as being uncomfortable and inconvenient, amniocentesis carries a small risk of miscarriage or infection.

With the new test, scientists only need to draw a small amount of blood from the woman. The blood is analysed and the results are available within a couple of days, said Quake, who is a bioengineer at Stanford.

Quake said this test is not only safer than invasive techniques but can also make a determination at an earlier gestational age, around 12 weeks.

In a statement, Carol Boys, chief executive at The Downs Syndrome Association said "There is no question that these non-invasive tests will be introduced in the next few years. It's therefore incredibly important that potential parents are given accurate information on Down's syndrome before they make a choice about whether to terminate or not. We don't consider Down's syndrome a reason for termination, but we recognise that bringing up a child with Down's syndrome isn't right for everyone. The more informed parents are, the better the position they are in to make the choice that is right for them."

For further information on Downs Syndrome visit www.downs-syndrome.org.uk