Sequenom Still Very Good, Just No Longer Perfect

Updated from 10:13 a.m. EST

A prenatal genetic screening test for Down syndrome being developed by Sequenom (SQNM - commentary - Cramer's Take) no longer has a perfect track record.

The San Diego-based genetics-testing company said Wednesday night that its experimental SEQureDx test recorded one false positive from a new batch of 459 blood samples collected from pregnant women at high risk for giving birth to a Down syndrome baby.

Shares of Sequenom were down 2.1% Thursday to $22.13.

Until now, Sequenom's test had a 100% detection rate for Down syndrome and a 0% false positive rate when used in just under 400 pregnant women -- a perfect record. While Wednesday's disclosure of one false positive test in more than 858 total samples mars that flawless performance, Sequenom CEO Harry Stylli says an overall false positive rate of one-tenth of 1% is significantly better than current prenatal screening methods for Down syndrome, which can have a false positive rate of around 5%.

"The test is performing better than we expected at this point in the game, and from a statistical perspective, the test has actually gotten stronger from where it was previously," he said. "As we increase our sample size, we expected to have false positives and false negatives, so to have a 100% detection rate and only one false positive is a better performance than I thought we would have," he added.

A false positive means that a pregnant woman is told she may be carrying a child with Down syndrome when in fact, her unborn baby does not have the genetic disease. False positives from screening tests like these are problematic because women then go on to confirm the diagnosis unnecessarily with invasive procedures like amniocentesis, which carry a small risk of miscarriage.

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At the time of publication, Feuerstein's Biotech Select model portfolio had no positions in stocks mentioned.

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