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24 Clinical OMICs July/August 2017 www.clinicalomics.com Dr. Singh said that the company plans to roll out its cell-based nonin- vasive prenatal diagnosis tests to six different regional hospitals in Den- mark later this year. "This will the first time since 1969, when using fetal cells for chromo- somal aneuploidy detection was first proposed, that pregnant women will get an opportunity to opt for cell- based noninvasive prenatal diagnosis in a clinic," he said. Although it is a smaller field than that of cfDNA testing, a number of other groups are developing cell-based prenatal tests. Shuang Hou, Ph.D., a researcher at UCLA is working on enriching circulating fetal trophoblast cells using "NanoVelcro Microchips" and then isolating them using laser capture microdissection. Similar to Dr. Beaudet, he says that while the technique is working rea- sonably accurately in the lab, scaling it up to use in the clinic is the next step. "Our plan is to push it to the market in 2 or 3 years to make sure that peo- ple can use it, I'm not sure what kind of technical problems we are going to encounter, but that's our plan." Researchers from Wayne State Uni- versity School of Medicine also pub- lished work last year showing they could profile fetal trophoblast cells extracted from the endocervical canal (in a technique similar to that used in the Pap smear test) at five weeks' gestation. Future Directions In the coming years, it seems likely that use of cfDNA testing will expand and also become more accurate for rare conditions. It also seems probable that at least one of the teams develop- ing cell-based tests will have achieved a "clinic-ready" test within the next couple of years. Dr. Lo believes that taking into account the various recently discov- ered characteristics of fetal DNA, such as the size of the fragments, specific cutpoints, and methylation status (fetal DNA is generally hypomethylated) can help develop more accurate cfDNA tests for a wider range of disorders. One somewhat neglected area he hopes will expand is testing for mono- genic disorders, such as congenital adrenal hyperplasia, using cfDNA. He thinks one reason these tests have not been widely commercial- ized could be because assays would ideally need to be tailored to specific groups or families, but says that this shouldn't be an insurmountable issue if a company really wished to develop this further. In a bid to make cfDNA tests more accessible in low-resource settings, European noninvasive prenatal test- ing company LifeCodexx recently cre- ated a cfDNA platform using qPCR. "This technology can provide the basis for an affordable, cost-efficient noninvasive prenatal testing solution that could be deployed with mini- mal investment around the globe in a local and decentralized manner," CEO Michael Lutz, Ph.D., explained. Notably, the company's more expensive PrenaTest currently tests for DiGeorge syndrome in addition to more common abnormalities. When asked about how accurately the com- pany's test is at detecting the deletion, Dr. Lutz commented: "Since DiGeorge syndrome was introduced about one- year ago, we have not experienced any false-positive or false-negative results so far." When considering the future of non- invasive prenatal testing, Dr. Beaudet commented: "I would like to see a next phase in which we try to sequence the entire fetal genome or certain parts of the fetal genome to find de novo point mutations, which can be very del- eterious and altogether account for maybe five times as much disability as Down syndrome. "Our lab has launched a test that's beginning to look for these mutations, which are highly correlated with the age of the father," he added. Dr. Singh believes that "a simpler, safer, and accurate prenatal diagnosis based on fetal cells is the future." In a challenge to proponents of cfDNA testing, he commented: "In the near future, we see cell-based non- invasive prenatal diagnosis taking over from cell-free noninvasive pre- natal testing. In the long run, it will replace invasive prenatal diagnostics methods." (continued from page 22) Li Ka Shing Institute of Health Sciences Dennis Lo, Ph.D., M.D., surrounded by his team at the Chinese University of Hong Kong.