New Blood Test Detects Down Syndrome
California Researchers Find Baby's DNA in Mother's Blood
Oct 29, 2008
Just published in the journal Proceeding of the National Academy of Sciences, Stanford University scientists have devised a blood test that will be able to detect even the tiniest amounts of the baby's DNA in the mother's bloodstream.
Current Options for Prenatal Testing of the Baby's DNA
Currently parents have the option of using a screening tool such as the AFP test that looks for certain hormones in the mother's blood. The AFP alone is not a reliable diagnostic tool and can only give a mother information about her statistical likelihood of carrying a baby with Down Syndrome. If results with an AFP are not conclusive, then parents are often led to much more invasive testing such as amniocentesis to identify the actual chromosomes in the amniotic fluid. With a 1% risk of miscarriage, amniocentesis is definitely not risk-free.
The only other option for genetic testing now is known as chorionic villus sampling (CVS), which involves extracting a piece of placental tissue. This test has a small risk for causing anomalies in the baby such as missing fingers and toes if it is performed too early. This new blood test developed by Stanford scientists will allow for detection of the baby's DNA in the mother's blood without the risks associated with CVS or amniocentesis.
When can the blood test be performed?
Dr. Stephen Quake, lead physician conducting this research, believes that they may be able to use this blood test as early as 5 weeks of pregnancy. Currently the cost for doing the sequencing of the chromosomes in the mother's blood would run about $700, but the prices are expected to drop by the time the test is available to the general public. The blood test is currently being patented and will be tested on several hundred women before being made available as a routine procedure.
What to do with the prenatal test results?
The only question will still remain for expectant parents is what to do with the test results once they have them. While parents can benefit from knowing sooner if there are genetic problems with their baby, it still forces parents to make a decision. Some care providers recommend that parents do not begin any prenatal testing, even screening tools, if they would not consider doing an abortion. Some parents may want to do prenatal testing so that they can be better prepared for raising a special needs child. Or some parents will want to know if there are problems early since they would abort a child with a known genetic disorder.
A good rule of thumb with regard to prenatal testing is to consider every path you would take based on the result you get before you start down the road!
