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Researcher Outlines Clinical Challenges with New Genomic Prenatal Dx Technologies

NEW YORK (GenomeWeb News) – With the arrival over the past year of several new prenatal genetic diagnostic tests and recent advances in sequencing the fetal genome, genomic medicine has begun to show how it may be used to diagnose diseases in fetuses early in pregnancy and with high accuracy, but it also is posing new challenges for medical communities and parents, according to a review published online in Nature Medicine today.

Information gleaned from gene expression arrays and non-invasive prenatal DNA testing (NIPT) have just begun to change prenatal diagnostics, and prenatal medicine certainly will be expanded to harness genetic, genomic, and transcriptomic data, but there are a range of issues that should be addressed as these new tools advance, Diana Bianchi, a Tufts Medical Center professor of pediatrics, said in the review.

Sequenom jumped into the prenatal genetic diagnostics market with the launch last year of its MaterniT21 Plus test, which uses Illumina's HiSeq sequencing platform to diagnose fetal aneuploidies including trisomy 21, 18, and 13. Other entrants have swiftly jumped into the field, including Verinata Health and Ariosa Diagnostics, and another firm, Natera, is expected to launch its test later this year.

In addition, Fluidigm and Novartis had entered into a collaboration to develop a microfluidics-based test for fetal aneuploidies. However, that alliance has ended and rights that had been granted to Novartis have reverted back to Fluidigm.

Bianchi, who is a scientific and clinical advisory board member at Verinata Health and executive director of the Mother Infant Research Institute at Tufts, explained in an interview with GWDN this week that these new prenatal diagnostic technologies have "accelerated" into clinical care very quickly and are presenting challenges to obstetricians and gynecologists.

Genetics-based testing to detect trisomy 21, monosomy x (Turner syndrome), or other aneuploidies offers the potential to identify disorders earlier and with greater certainty than current methods, but the medical and healthcare communities will need to prepare for these changes, Bianchi said.

"Most healthcare providers really don't have a good idea of what is going on [with genomic NIPTs] and what it means for the present and the future," she said. "Prenatal diagnosis in general has been operating in a well-established fashion, using well-established screening and diagnostic techniques for thirty years. And now there's a paradigm shift."

That shift is just beginning. But, according to Bianchi's estimate, somewhere between 15,000 and 20,000 of these tests have been performed between the three companies offering these tests in the US since they first launched late last year. In early May, Sequenom officials said that the 52-week run rate for their test alone was more than 45,000.

The safety of these tests is a big selling point for pregnant women, Bianchi said. "The real implication of these tests is that you are going to reduce significantly the number of invasive procedures that are performed." They could be used to avoid amniocentesis, for example, which carries with it a "small but measurable chance of miscarriage," Bianchi wrote in the article.

The genomic tests also are more accurate, but they are more expensive, and possibly due to their novelty and cost many health insurance companies have not yet developed policies for covering them, Bianchi explained, saying that they are taking a "wait-and-see" approach to these tests until more experience accumulates in the field.

Bianchi believes that experience and knowledge about these NIPTs, and genomic literacy in general, will be critical for health care providers.

"Women are reading about these tests online, and they are going to their providers and asking about them," she said. "So, the frontline obstetrical care providers need to know about it. The genetic counselors need to know about it. The maternal fetal medicine physicians need to know about it. The neonatologists need to know about it. And nobody's learned about it in medical school because none of this technology was available when they were in medical school."

Each company has different techniques, such as the sequencing approach or the type of bioinformatics analysis they use, and the healthcare providers need to be able to help patients understand their results and how they work.

"These tests are progressively getting more and more complex, and if anything has become obvious in the last few years it is that there is an ever-widening gap between the technological advances and education," Bianchi told GWDN. "The technology can tell you amazing things about the fetus, but what good is it if the average healthcare provider doesn't understand what it means."

Education and training are obvious needs to help get workers up to speed on the new testing, but other issues and challenges Bianchi identified may not be so simple to resolve.

Bianchi sees a range of issues that need to be addressed. Standards and guidelines are needed to help address some concerns, such as questions about how to handle information about genetic risk in a fetus for a disorder that does not set in until adulthood. Physicians may also find out information about paternity or incest from chromosome microarrays that was not even sought, and policies need to address such situations. She also sees the potential that someone may feel coerced to take such genetic tests by providers, peers, or insurers.

In addition to the issues surrounding the new genetic tests are challenges to developing personalized fetal therapies. For example, there is a pressing need for age-appropriate gene expression data, as most of the publicly available datasets cover adults. And the massive amounts of data from fetal genome, proteome, and transcriptome studies will need to be integrated with epigenomic knowledge, Bianchi noted.

"One of the really important benefits of all this testing is it is really leading us in the direction that we should be able ultimately to make a diagnosis and give a medicine to the pregnant woman and begin treating the fetus in utero," she said, adding that such treatments are "certainly feasible in the next few years."

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