In a major breakthrough, a new blood test has been developed that demonstrates 100% sensitivity and 100% specificity in all normal and Down's syndrome pregnancies examined to date.

There is no commercial test available yet, but at least one company hopes to introduce one in the U.S. within about a year. When this test becomes available, testing for Down's Syndrome in fetuses will no longer be risky, harmful and dangerous for mothers. The test will not just be necessary for "high risk" patients, allowing all affected parents to identify and prepare for this life changing condition early on.

Over the last 20 years, new technology has improved the methods of detection of fetal abnormalities, including Down's Syndrome. However, these methods have been risky to expecting mothers as a fetal tissue sample needs to be obtained by amniocentesis or chorionic villus sampling which can lead to an increased risk of miscarriage and other complications.

At present all pregnant women are offered screening to see if their baby is at risk of Down's syndrome. For a firm diagnosis, doctors must take a sample of amniotic fluid or the placenta, which involves a 1 in 100 risk of miscarriage.

Scientists from Cyprus, Greece and Britain said the new technique correctly identified 14 Down syndrome cases and 26 normal fetuses in a blind test. They believe it will also be possible to diagnose the condition earlier on.

Study author Philippos Patsalis, of the Cyprus Institute of Neurology and Genetics, said:

'The method is simple and fast and easy to perform in every genetic diagnostic lab worldwide because it does not require expensive equipment, software or special infrastructure."

In the 1980s and 90s, the results of the prenatal tests were expressed to parents as "high risk" and "low risk," depending on whether the risk result was above or below an arbitrary cutoff point at 1 in 250. The reason for choosing that cutoff value was based on the risk of complications from an amniocentesis procedure. If the mother's risk was less than 1 in 250 of having a child with Down's Syndrome, then the risk of amniocentesis was greater and the mother was called "low risk." Likewise, if the mother's results showed a greater risk than 1 in 250, the pregnancy was called "high risk."

Over the last two decades, the screening was done between the 15th and 20th week of gestation, but it was most accurate between the 16th week and the 18th week. However, research in the last 6 years has concentrated on finding a way to screen in the first trimester to enable parents to have time to make choices when given the results of a positive screen test. The first trimester screen now uses a combination of the maternal age, the serum quadruple screen, the serum marker PAPP-A and an ultrasound measurement of the back of the neck of the fetus. When used correctly, this first trimester screen has a detection rate of approximately 95% of all cases of Down's Syndrome, with a false-positive rate of 5%.

This new blood test will take the complication and risk determination out of the process and all expecting mothers will be able to be easily tested.

Down's Syndrome is a genetic disorder that causes physical and learning disabilities and raises the risk of heart disease. Infants with the condition have three copies of the Chromosome 21 instead of the normal two.

Down's affects about one in every 700 live births but women of 40 are 16 times more likely to have a Down's child than a 25-year-old.

For the full study report published by Nature Journal, click HERE.

Sy Kraft, B.A.