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Sequenom Validates MaterniT21 for Trisomy 18 and 13 Detection

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This article was originally published Feb. 3.

Sequenom has published the results of a study demonstrating that its noninvasive MaterniT21 test, which detects Down syndrome in a fetus by sequencing maternal plasma, can also detect trisomy 18 and trisomy 13.

The company, which launched its test in October, has reported previously that it could also detect trisomy 18 and 13, but with the caveat that the results were not statistically powered (CSN 10/19/2011). The new study, published online last week in Genetics in Medicine, now validates the test for these other aneuploidies.

The study "provides further evidence that this valuable noninvasive technology can identify nearly all cases of T18 and T13, as well as T21, at a low false-positive rate," Sequenom's CEO, Harry Hixson, said in a statement.

Researchers from the Women and Infants Hospital in Rhode Island led the study, which was part of the same trial as Sequenom's trisomy 21 trial, but published separately.

The original trial collected plasma samples from 4,664 women in either the late first trimester or early second trimester. Of those, nearly 1,700 samples were analyzed, including 212 cases of trisomy 21.

From those samples, the researchers detected 62 cases of trisomy 18 and 12 cases of trisomy 13.

They then designed a nested case/control study, which included the 212 trisomy 21 cases and euploid controls, as well as the trisomy 18 and 13 cases that had been detected and their matched controls, for a total of 1,988 pregnancies. Of those, 17 samples could not be analyzed primarily because the samples had a fraction of fetal DNA below 4 percent.

The interpreted pregnancies included 59 cases of trisomy 18, 12 cases of trisomy 13, 212 cases of trisomy 21, and 1,702 euploid pregnancies. All 59 cases of trisomy 18 and 11 out of 12 cases of trisomy 13 were called correctly, with false-positive rates of 0.28 percent and 0.97 percent, respectively.

Calling trisomies relies on an analysis known as a z-score, which is essentially a method for counting chromosomes. Trisomy is called when the z-score is above three, but the authors found that raising the cutoff could lower the false-positive rate to 0.1 percent, with an overall detection rate of 98.9 percent.

Following the publication, several analysts maintained their respective ratings of the company. Elemer Piros, an analyst with Rodman and Renshaw, wrote in a research note that the publication "continues to validate the use of MaterniT21 LDT in detecting fetal trisomies," and said that the firm would maintain its Market Perform rating.

Oppenheimer maintained its Outperform rating, and analyst David Ferreiro wrote in a report that the "extra diagnostic criteria" gives Sequenom an "edge over competition," noting that Aria Diagnostics and Verinata Health, which are both developing trisomy 21 tests that they plan to launch this year, have not yet published data on trisomy 13 detection.

Natera, another firm developing a sequencing-based prenatal Down test, announced this week after the publication of the Sequenom study that it plans to release data on its test's ability to detect trisomies 12, 18, and 21, as well as "certain sex chromosome abnormalities," later this month at the Society for Maternal-Fetal Medicine's annual meeting.

Ferreiro added that while the trisomy 18 and 13 detection is "not a critical factor driving test volume, we are encouraged by the continuing positive news" for Sequenom.

Additionally, he said that Oppenheimer expects Sequenom to perform 8,443 tests for $15.2 million in revenue this year, with a "significant ramp" in 2013, at around 35,000 tests for $64 million in revenue.

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