June 4 (Bloomberg) -- Sequenom Inc., a genetic-analysis provider for biomedical research and agriculture, rose the most since 2005 in U.S. trading after it said a device that detects Down syndrome before birth worked without giving false-positive results.

In studies involving about 200 samples, Sequenom's proprietary test identified all Down-syndrome swatches, the San Diego-based company said today in a statement. Sequenom will continue to develop the test this year and plans to sell it in the U.S. in the first half of 2009.

The result ``blows expectations away,'' Elemer Piros, an analyst with Rodman & Renshaw Inc. in New York, wrote in a note today. ``Sequenom's platform could usher in an entirely new paradigm in which a single test could replace the current range of surrogate marker methods that must be employed to obtain reliable results.''

Tests on the market today have Down-syndrome detection rates of 70 percent to 90 percent with about a 5 percent false- positive rate, Sequenom said. Current methods of detecting the disorder can be invasive, requiring the mother to undergo a serum screening in the second trimester, the company said.

``We are very pleased to be reporting substantial progress toward commercializing an important test to screen for Down syndrome that can be administered as early as late in the first trimester through a simple blood draw from the mother,'' Chief Executive Officer Harry Stylli said in the statement.

Down syndrome is a genetic disorder that can cause mental retardation and stunted growth and occurs in one out of every 733 live births. More than 400,000 people in the U.S. have the condition, according to the National Down Syndrome Society.

Sequenom rose $1.67, or 22 percent, to $9.33 at 4 p.m. New York time in Nasdaq Stock Market trading, for the biggest gain since Sept. 30, 2005. The increase narrowed the stock's decline for the year to 2.3 percent.

To contact the reporter on this story: Kelly Riddell in Washington at Kriddell1@bloomberg.net.

Last Updated: June 4, 2008 16:23 EDT