The Federal Trade Commission has asked Swiss pharmaceutical company Roche Holding AG for more information related to its $5.7 billion hostile takeover offer for diagnostics company Illumina Inc.

Illumina’s board unanimously turned down Roche’s offer last month, saying it was “grossly inadequate” and that shareholders should not tender their stock to Roche. The board also said that Roche was not properly valuing the growth potential of Illumina’s business, its products in development and its track record.

Roche went public with its $44.50 per share offer in January after Illumina refused to enter negotiations. Illumina then adopted a “poison pill” measure intended to ward off unwanted attempts to acquire the company.

Illumina shares are trading well above the offered price, closing at $50.34 per share on Tuesday.

Illumina, which is based in San Diego, makes systems that analyze an individual’s DNA, and it is the biggest gene-sequencing company. It’s expected that future breakthroughs will use that information to tailor treatments in ways that are especially effective for people with certain genes.

Roche said Tuesday that the FTC is looking for more information on its microarray business. The request extends the waiting period on the proposed deal by 10 days after Roche gives the FTC the information it asked for, unless voluntarily extended by Roche or ended sooner by the FTC.

Roche said that it will continue to cooperate with the FTC.