Down syndrome test
January 6, 2012
Today, in Germany, an estimated 100,000 people are affected by Down syndrome. This condition, where children are born with additional genetic material on the 21st chromosome, often results in cognitive impairment in the child and nearly a lifetime of extra care and support by family members and care givers.
When a pregnant woman wants to be sure that her unborn child does not have Down syndrome, her doctor can perform an amniocentesis, where a small amount of amniotic fluid is drawn from the mother. But that procedure presents a small risk to the pregnancy, so many women are reluctant to undergo it. In Germany, only 70,000 women receive an amniocentesis each year.
"The amniocentesis carries a risk of 0.3 to 1 percent, that by the intervention itself a miscarriage can be triggered," said Dr. Michael Entezami, a gynecologist at the Center for Prenatal Diagnosis and Human Genetics in Berlin.
However, this year, a new blood test should become available in Germany that can screen for Down syndrome.
The results from an early trial of a Down syndrome blood test were conducted in Cyprus were published in the journal Nature Medicine in March 2011. The test has been available in the United States since October 2011.
"Such a non-invasive approach will avoid the risk of miscarriages of normal pregnancies caused by current, more invasive procedures," the scientists wrote in the March 2011 paper.
Blood test should be offered after other tests
A pregnant woman's blood contains not only her own genetic material, but also about five percent fetal genetic material from disintegrated cells of the placenta. In general, the placental tissue is genetically identical to the tissues of the child - which means that doctors can scan for the presence of genetic errors.
By scanning this genetic material, medical officials can then calculate if there are genetic duplications which would cause Down's syndrome. Dr. Entezami says that this test is accurate 98 percent of the time, but also recommends that mothers receive the blood test in conjunction with other tests.
"The blood test is a [step up] for us," Dr. Entezami told Deutsche Welle.
Author: Marieke Degen / cjf
Editor: Gudrun Heise / sjt