Since then, Myriad has sued at least six other companies or been sued by them over plans to offer competing tests. Those cases all have now been consolidated in Shelby's court.
In denying the preliminary injunction request, Shelby ruled that Ambry "has raised substantial questions concerning whether any of the patent claims at issue … are directed toward patent eligible subject matter."
A Myriad spokesman said the company was not surprised by the ruling because courts rarely grant preliminary injunction requests. The company believes it ultimately will win, said spokesman Ron Rogers.
"The court did not rule on the actual merits of the case," Rogers said Tuesday. "That will be decided at a future trial or future court proceedings."
Ambry Chief Executive Charles Dunlop said the company was "exhilarated" by the ruling, which was filed Monday. He said the decision "is a victory for the entire genetics community" and said the company would continue offering competing tests while the case remains pending.
Myriad's shares fell $3.15 Tuesday, or 8.3 percent, to close at $34.60.
Myriad for 17 years has been the only company to offer the tests of the genes, the mutation of which spell a very high likelihood of developing a breast or ovarian cancer.
Shelby, in a detailed 106-page ruling, said that Myriad likely would suffer a loss of revenue as a result of competition by Ambry, which is offering the tests for $2,200 compared to Myriad's $3,340 , but pointed out Myriad had still forecast increased growth.
"Myriad has enjoyed an exclusive monopoly in the BRCA1 and BRCA2 testing market for nearly two decades, and its own financial forecasts show that it expects to see increased revenue growth this year," the judge wrote.