The Securities and Exchange Commission has initiated an investigation into employee data mishandling at Sequenom, according to a June 30 regulatory filing.

In April, the San Diego-based maker of prenatal tests revealed that it could no longer rely on data or results of a study testing its SEQureDx technology in unborn babies for Down syndrome. Sequenom began an internal investigation into the matter, which is ongoing, it said.

The company originally planned to launch SeQureDx in June, but has postponed its introduction, along with other prenatal tests for rhesus D, cystic fibrosis and gender, as it sorts everything out.

Sequenom has faced a slew of shareholder lawsuits since it first announced the employee mishandling April 29. Angry investors have filed at least 15 separate lawsuits in Southern California.

Sequenom said it intends to “cooperate fully” with the SEC in its investigation.

Shares of Sequenom, traded under the symbol SQNM on Nasdaq, were down about 4 percent in midday trading July 1 at $3.77. The company’s stock has plummeted about 74 percent since it announced the employee mishandling.

— Heather Chambers