Prenatal DNA testing has been a fiercely contested market of late. Yet another competitor entered the fray last week when Natera, a startup based in San Carlos, California, announced the 1 March launch date of a commercial test that can detect chromosomal abnormalities in the developing fetus from just a drop of an expectant mother’s blood—and with a sensitivity on par of that of more invasive techniques such as amniocentesis and chorionic villus sampling, both of which carry an elevated risk of miscarriage.
Natera now joins three other California-based firms—Sequenom, Verinata Health (a division of sequencing giant Illumina) and Ariosa Diagnostics—in offering such products for women at high risk of having babies with Down’s syndrome or other chromosomal miscounts known as aneuploidies. With US health insurers, including Aetna and Wellpoint, saying they plan to cover the new tests, the market for DNA-based prenatal screening now provides “a billion dollar opportunity,” according to David Ferreiro, an analyst at Oppenheimer & Co. in Boston.
Between the four new tests, Verinata’s and Sequenom’s currently offer the widest range of screening options, with the ability to identify disorders associated with an extra X or Y sex chromosome, such as Klinefelter’s (XXY) and triple X syndrome. This flexibility is reflected in the cost: Sequenom’s MaterniT21 PLUS carries a list price of $2,762, almost twice as much as Natera’s Panorama, which can detect a missing X chromosome but not other kinds of sex chromosome irregularities.
The tests’ sensitivities vary depending on the chromosome, but all companies claim to be able to identify a fetus with Down’s syndrome, caused by three copies of chromosome 21, more than 99 times out of 100. Detecting extra copies of chromosome 13—a condition known as Patau’s syndrome—is more difficult, and Ariosa’s Harmony test does poorest here, with only 80% sensitivity. But it’s also the cheapest, with a sticker price of just $795 (see chart for the full comparison).
For now, the DNA-based tests are only thought to provide a screening tool for select populations, and are not considered definitively diagnostic by clinician groups such as the National Society of Genetic Counselors, who worry about the possibility of erroneous results, the lack of data in low-risk populations and the limited number of aneuploidies tested. Thus, most experts—and many of the companies themselves—still recommend that women whose DNA-based tests come back positive follow up with conventional tests such as amniocentesis. Although the additional testing will still mean invasive procedures for some pregnant women, and their attendant complications, “you are limiting those invasive tests to only the high risk groups,” says Joan Scott, a genetic counselor and executive director of the National Coalition for Health Professional Education in Genetics in Lutherville, Maryland.
Ultimately, “women and their providers [need to be] well informed about the benefits and limitations that are inherent in all these tests,” says Scott. “It’s not a cut and dried decision.”
A version of this story appears in the April 2013 issue of Nature Medicine.