A noninvasive prenatal test for Down syndrome and other fetal abnormalities has been launched by Verinata Healthcare, of Redwood City, California, for use by clinicians in the US. The genomic test called verifi uses maternal blood and massively parallel sequencing to identify telltale chromosomal abnormalities in circulating cell-free fetal DNA. Steve Quake, a professor at Stanford University's School of Engineering, whose laboratory generated the technology upon which verifi is based, says he hopes the test will one day replace more invasive procedures like amniocentesis and chorionic villus sampling, which confer a risk of miscarriage. A recent study of 2,882 patients using verifi showed 100% specificity and sensitivity for trisomy-21; the assay also reliably detected other chromosome number problems including 18, 13, 20, 16, X and Y. The assay is very similar to the MaterniT21 test launched late last year by San Diego–based firm Sequenom, and indeed, a patent-related legal dispute is pending between the two companies. Other companies have tests on the horizon. Stephen Brown, a reproductive geneticist at the University of Vermont, as well as a physician who uses MaterniT21 in the clinic, says that the science behind the Sequenom and Verinata tests is “indistinguishable.” Having studied the patent involved in the dispute, Brown doesn't think a lawsuit will stop either company from carrying on. What will tip the market, he says, will be the usual mundane factors: customer service, turnaround time and price.