The effectiveness of a prenatal test for Down syndrome has been thrown into doubt after its developers, Sequenom, admitted that study data had been 'mishandled' by its employees. The company, which had been producing apparently strong results in house for its DNA and RNA blood testing products, has now made clear that the results of these studies are not to be relied upon.

The loss of confidence in the test was clearly reflected in the market's response, with shares in the company collapsing from $14.91 to $3.62. In response to the employee misconduct, which has resulted in four suspensions, the company reported itself to both the Food and Drugs Administration and the Securities and Exchange Commission. The test itself, called SEQure Dx, was considered to be central to the company's success and had been due to be launched in June, but investors must now wait for results of independent clinical trials not due to be completed until early 2010.

The discredited in house trials had indicated that SEQure DX could detect the presence of Down syndrome in 96.6 per cent of cases and could predict the absence of Down syndrome with 100 per cent accuracy. The strength of these, non-peer-reviewed, results had raised questions about their reliability, concerns that have now been clearly substantiated.

The resulting delay in the availability of the test is a setback not just for the company but also for health services and patients who are waiting in anticipation for what has been hailed as a safer, less invasive and cheaper alternative to currently available testing procedures (principally chorionic villus sampling and amniocentesis). Whether SEQure DX is actually of comparable accuracy to these existing procedures is now a question for independent inquiry.

The new external trial will involve 15,000 women, rather than the mere 858 involved in the Sequenom trials. The independent tests will run concurrently with another Sequenom trial, aiming to vindicate the validity of their previous tests, with that trial hoping to yield results before the end of the year. Whatever the findings, however, any production ready test had been delayed by at least twelve to eighteen months and, for now, the credibility of Sequenom and in-house trials have been significantly undermined.