A new non-invasive test for detecting Down syndrome was announced recently and reported in this NY Times article. This new test by Sequenom tests for Down syndrome by testing a sample of the mother’s blood rather than the more invasive tests of amniocentesis or CVS (chorionic villus sampling) which are the routine tests currently performed to check for chromosomal abnormalities, both of which carry risk of miscarriage.
According to a recent study published by the journal Genetics in Medicine, this new test was 98.6% accurate in picking up Down Syndrome cases, with a less than .02% risk of a false positive. However, in the cases where Down Syndrome is detected, further invasive procedures that test all chromosomes are often recommended for additional confirmation.
Because the test does not pose a risk to the fetus and because it can be used as early as 10 weeks of pregnancy (earlier than both other current tests) experts believe it may result in fewer of the more invasive procedures being performed. The drawback is that the test is not able to detect other chromosomal abnormalities, including a few rare forms of Down Syndrome that do not have three copies of chromosome 21.
The controversy (and potential medical ethics question) that arises is whether tests such as these will lead to more pregnancy terminations when Down Syndrome is detected, which would lead to diminished support and services for those currently living with this condition.
Two other companies have announced plans to release similar tests in 2012, and with the technologies that are being utilized for genetic analysis in these tests, we can expect future tests that may make it possible to prenatally diagnose abnormalities that do not involve extra chromosomes.