Investors sue Sequenom over Down Syndrome test delay

*At least five investor lawsuits filed against Sequenom

*Company will fight "vigorously" but faces material risks

LOS ANGELES, May 4 (Reuters) - Investors have filed several lawsuits accusing Sequenom Inc (SQNM.O) and its officers of federal securities violations related to its April 29 announcement that it would delay launching its prenatal Down Syndrome test due to mishandling of data by some employees.

Sequenom on Monday acknowledged the filing of "several" suits, which it said could have a "material adverse impact" on its business or results if it should not prevail in court.

Shares of Sequenom fell nearly 80 percent to a two-year low the day after the company said none of the research and development data for the SEQureDx Down syndrome test could be relied upon, and also delayed the launch of three other tests in order to review all test data.

At least five proposed class action lawsuits were filed against Sequenom in Los Angeles federal court on Friday, by law firms Coughlin Stoia Geller Rudman & Robbins and Johnson Bottini of San Diego, Izard Nobel of Connecticut, Brodsky & Smith of Pennsylvania and Stull Stull & Brody of New York.

All five complaints allege that the defendants inflated Sequenom's share price by issuing materially false and misleading statements about the Down syndrome test.

The proposed class includes investors who bought or owned Sequenom shares between June 4, 2008 and April 29. The plaintiffs seek unspecified damages.

On Monday, Sequenom said in a securities filing that it planned to "vigorously defend against the claims" but that it "could be forced to make significant payments to our stockholders and their lawyers" if it does not prevail in the litigation.