Most people do not think of fetuses as tumors. But it was this idea that revolutionized how scientists approach prenatal tests.
When Dennis Lo, a professor at the Chinese University of Hong Kong, attended a lecture on cancer in 1997, he realized that the unborn child can be thought of as a foreign entity in much the same way that tumors involve the presence of foreign DNA.
It was this idea that led Sequenom, Inc. to develop a test to identify certain chromosomal abnormalities — specifically Down syndrome, Edwards syndrome and Patau syndrome, all of which involve an extra copy of a non-sex chromosome. If carried to term, children with these syndromes often show impaired mental and physical development.
A study published last month in the journal Genetics in Medicine determined that the test could reliably identify these syndromes in utero. The researchers — some of whom are affiliated with Alpert Medical School — studied pregnant women at 27 different clinical sites around the world.
The study got off to a less-than-auspicious start when Sequenom, who funded the study, came under fire after one of its lead researchers was convicted of faking data, said Glenn Palomaki, an associate professor of pathology and laboratory medicine at the Med School, who led the study. Then there was the costly matter of transporting samples from around the world.
The samples had to be shipped in dry ice and processed by customs, said Jacob Canick, professor of pathology and laboratory medicine at the Med School and one of the study's authors. "So we learned a lot about companies that expedite movement through customs," he said.
The researchers found that the test — which involves taking a few tubes of blood from the pregnant woman — is far more accurate than current screening tests and offers a very low false-positive rate. It is not an invasive procedure, decreasing the risk of harm to the woman and her fetus, Palomaki said. But due to the existence of false-positives, women who get positive results with this test should undergo invasive procedures as well, he added.
Invasive procedures are known to cause miscarriages at a rate of approximately 1 out of every 200 procedures, Canick said.
Since the conclusion of the study, Sequenom has begun to offer the test clinically, starting with women at an increased risk. Several other companies may soon offer similar tests, Canick said.
There are, however, a few roadblocks before this test can become widely used, Palomaki said, adding that it is very new and its expenses are not yet covered by insurance companies.
The turnaround time is also not as quick as for standard screening tests, Canick said. "In three to five years, the cost will be way down, and it may in fact be something all pregnant women could have if they choose."
Rossa Chiu, a pathologist at the Chinese University of Hong Kong, said this test means "that technology has the potential to look for abnormalities on other chromosomes" in addition to the three implicated in the chromosomal syndromes the researchers studied.
