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A US federal judge in October invalidated patent claims for a noninvasive prenatal test marketed by San Diego–based Sequenom. The decision is part of an anti-patent trend in the courts that has left everyone in the biotech community unclear on which diagnostic method claims are patent-eligible. Sequenom's patent covers methods to detect cell-free fetal DNA (cffDNA) in a pregnant woman's bloodstream. The technology gives women a noninvasive way to test their unborn children for chromosomal defects such as Down syndrome. Older methods are less accurate or carry a slight risk of miscarriage because they involve sampling tissue or fluid from the womb (Nat. Biotechnol. 31, 595–601, 2013). Sequenom was first to the market with the test, in 2011, and has been trying to lock out its numerous competitors by claiming they infringe on the test's central patent. In the ruling, Judge Susan Illston of the US District Court in Northern California said Sequenom's patent was invalid because cffDNA is a natural phenomenon, and because the company's methods for detecting it involve routine DNA amplification and detection techniques. Illston also said the patent posed a risk of preempting other uses of cffDNA because there is no commercially viable alternative for detecting it. The judge cited several US Supreme Court decisions, including a June 2013 decision involving Myriad Genetics in which the court ruled that naturally occurring DNA segments are a product of nature that cannot be patented (Nat. Biotechnol. 31, 663–665, 2013). She also cited a 2012 decision involving Prometheus Laboratories, in which the court ruled against another diagnostics patent, this one a method for determining the optimal dosage of a drug (Nat. Biotechnol. 30, 373–374, 2012). The Sequenom ruling is “not good news” for the biotech community, says attorney David Resnick at Nixon Peabody in Boston. “But it's not a surprise either,” he says. Resnick's advice to diagnostics makers: “Don't panic. It's a district court decision that is being appealed and hopefully the Federal Circuit will provide more clarity.” But taken together, the Myriad, Prometheus and Sequenom cases present a confusing and decidedly anti-patent landscape that may lead to trade secrecy in lieu of patenting, say attorneys. “If a client comes in and asks about patenting a test for detecting abnormalities during pregnancy, I may tell them not to patent,” says attorney Kevin Noonan at McDonnell Boehnen Hulbert & Berghoff in Chicago.