Prenatal Diagnosis of Down's Syndrome Is Minimally Invasive

In Down's syndrome, there are three copies of chromosome 21, called trisomy-21, instead of the normal two.

Taking advantage of differences in the DNA methylation patterns, which are important to control gene expression, between mother and fetus, a team of scientists at the Cyprus Institute of Neurology and Genetics (Nicosia, Cyprus) developed the new test. It involves taking only a small quantity of blood taken from the mother's arm, which is analyzed to detect DNA differences between the mother and the fetus.

The team used the method in a small trial that allowed them to diagnose correctly 14 trisomy-21 cases and 26 normal fetuses, highlighting its potential clinical utility.

Philippos Patsalis PhD, who led the study, said that the new method for prenatal diagnosis of Down's syndrome eliminates dangers involved with amniocentesis testing, which involves sampling amniotic fluid by inserting a hollow needle into the mother's uterus. This can result in spontaneous abortion. He said that the new method would be made available to the medical community after clinical tests are concluded worldwide on 1,000 women within two years.

At present, only women belonging to high-risk groups, including older women, are tested for Down's syndrome, which is the most common genetic cause of mental retardation.

The study was reported in the March 7, 2011 online edition of Nature Medicine.

Related Link:
Cyprus Institute of Neurology and Genetics