New Genetic-Based Prenatal Test Safer For Expecting Mothers Than Standard Tests

Here is another area where genetics can provide some much-needed relief: performing tests on expectant mothers to determine the possibility of Down syndrome in the fetus.

The new test is blood based, unlike some of the currently existing tests like amniocentesis, which involves testing the amniotic fluid itself. Amniotic fluid is extracted from the uterus, something extremely risky considering it exposes the mother to the possibility of infection and possible miscarriage.

The new test, conceived by scientists from Stanford University, the Howard Hughes Medical Institute, and the Lucile Packard Children’s Hospital, works on the principle of gene sequencing. It blows up DNA fragments present in the blood of the mother, some of which comes directly from the unborn baby. By examining the DNA the scientists are able to immediately detect the possibility of any chromosomal disorder being present in the fetus.

Speaking about the breakthrough test, professor of bioengineering and applied physics at Stanford and the Howard Hughes Medical Institute Stephen Quake said, “We look for chromosomes that are overrepresented. The breakthrough is we're able to measure very slight differences very accurately.”

If the new test works as well as the initial reports suggest, pregnant mothers can heave a sigh of relief. Currently, testing for chromosomal disorders is like a two-edged sword for these mothers-to-be - if they do test themselves, they run the risk of getting infected and even possibly suffering a miscarriage, or not doing the test and remaining unaware of the possibility of their child suffering from any genetic defects.

For the moment, the test seems to be working. The scientists who designed it have tested it successfully so far on 18 pregnant women and were able to pinpoint nine cases of Down syndrome, two cases of trisomy 18 and one case of trisomy 13. Both trisomy 13 and trisomy 18 are established genetic disorders.

The women who were tested were subjected to blood sampling between the 10th and 35th week of pregnancy. All of them also had one of the standard tests done prior to this new test.

The results of the new test were published Monday in the Proceedings of the National Academy of Sciences, but there is still a long way to go. The test will next have to go through clinical trials to prove its efficacy before it can be designated as safe to use.

Speaking further about the tests, Quake said the results had left him very excited. He said, “I got into this because I have a family, with two kids. With the first kid, we used amnio. With the second, we used CVS. Both were nerve-wracking experiences.”

Experts are being cautiously optimistic about the test, primarily because there have been other such ‘promising’ tests in the past that have finally petered out to nothing. Speaking about the test, test expert James Goldberg said, “The ability to diagnose fetal chromosomal disorders from maternal blood would be an important advance in the area of prenatal diagnosis.”

A founding fellow of the American College of Medical Genetics and part of Perinatal Associates Inc., a San Francisco based organization, Goldberg said that if the test worked, it would negate completely even the slight degree of risk associated with current tests.