Safer prenatal test for Down's syndrome launched in US

A new prenatal test that can detect Down's syndrome by using a sample of the mother's blood was launched in twenty US cities last Monday.

MaterniT21, developed by the San Diego-based biotechnology company Sequenom, analyses fetal DNA in the mother's blood as early as ten weeks into the pregnancy. The test reveals whether the fetus has three copies of chromosome 21 instead of the usual two — a genetic chromosomal anomaly known as trisomy 21 and the most common cause of Down's syndrome.

The test could potentially eliminate the need for riskier invasive procedures, such as amniocentesis and CVS. Invasive techniques require samples of either a small amount of fluid that surrounds the fetus or placenta, and carry a slight risk of miscarriage.

Dr Harry Hixson, Sequenom's chief executive officer (CEO), said: 'We believe that the MaterniT21 [test] will provide physicians and their patients with critical new information to help them make better informed decisions about the patients' healthcare and pregnancies'.

A study, sponsored by Sequenom, published the results of a trial of this new test in the journal Genetics in Medicine. Using blood samples from pregnant women, the test identified 209 of the 212 Down's syndrome cases, a rate of 98.6 percent. It incorrectly characterised three of 1,471 normal fetuses as having the disorder, earning a false-positive rate of 0.2 percent. The existing tests, such as amniocentesis and CVS, have a false-positive rate of up to five percent.

'It's better than anything by far that we've ever seen in testing for Down's syndrome non-invasively', said Jacob Canick, professor of pathology at Brown University and the senior author of the study.

MaterniT21 would be ordered by doctors, not directly by consumers, and the analysis would occur in Sequenom's laboratories. The test is expected to cost around $1,900, about the same as an amniocentesis. However, the company alleged that 'the out-of-pocket cost of the test for insured patients will be no more than $235', assuming that the insurers will pay the rest. It is not yet clear how willing insurers will be to cover this test, nor has it yet been approved by the US Food and Drug Administration.

Some experts have also raised concerns that the safer test could lead to more screening and more terminated pregnancies. However, although Sequenom 'hopes the test would be used by women who choose not to undergo invasive tests because of the risk of miscarriage', the company mentioned that women who test positive would still be advised to undergo the more definitive invasive tests before terminating a pregnancy.

Another company, Verinata Health, is expected to launch a similar product in the first quarter 2012. Gene Security Network, which is currently testing its prenatal diagnostic test to detect chromosomal anomalies, hopes to have a test ready later in 2012.

Sequenom was also involved in introducing a prenatal Down's syndrome test back in 2009. However, the company faced a scandal related to mishandling the key clinical data, which led to the removal of its top management, including the former CEO and research chief. The episode was followed by legal and regulatory probes into the matter.