June 30, 2010

Blood Test Could Detect Down’s Syndrome

Researchers say that a blood test during pregnancy could one day replace more invasive tests for Down's syndrome.

Women that are at high-risk are currently offered an amniocentesis test, which carries a risk of miscarriage.

However, Dutch researchers told a fertility conference that they are on the verge of developing an accurate way of testing the mother's blood for chromosome disorders in the fetus.

Experts said it was promising but too early to determine its effectiveness.

The test is based on a series of "probes" that attach to specific points on a chromosome.

The technique is that same that is already used in order to detect problems in fetal DNA in samples taken from amniotic fluid in the womb.

However, being able to test the mother's blood instead is non-invasive, quick and carries no risk for the fetus.

Delegates at the European Society of Human Reproduction and Embryology conference heard that the team has successfully identified the male or Y chromosome from the fetus in the mother's blood, proving their technique works.

They said the technique can be used as early as six-to-eight weeks.

They are now using the same principle to develop probes to detect the extra chromosome found in Down's syndrome.

The technique will be tested in women at high risk of an abnormal pregnancy that are already undergoing prenatal screening and invasive tests.

However, if proven to be accurate, the researchers hope that women will have access to the blood test within a few years.

Study leader Dr. Suzanna Frints, a clinical geneticist at Maastricht University Hospital, said that the costs of these types of tests are coming down all the time and could eventually be available for as low as $30.

"Blood samples can be taken during routine antenatal visits," she told BBC news.

"It is inexpensive compared to the costs of invasive prenatal diagnosis, and could easily be implemented at low cost."

She added, "At the moment, the reliability of the test is about 80% due to false negative results, but we are working to improve the accuracy."

Professor Stephen Robson, a spokesman for the Royal College of Obstetricians and Gynecologists, told BBC that there are labs around the world that are currently working on different techniques for these type of diagnostic tests.

"It is the holy grail of prenatal diagnosis to try and find a reliable method of diagnosing Down's syndrome and other chromosome abnormalities without doing invasive testing.

"This is another technique that could offer the potential to diagnose Down's syndrome non-invasively but it's important to emphasize that it is some years away."


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