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Updated from 9:27 a.m. EDT

Shares in



plunged in heavy trading Tuesday after the Food and Drug Administration told the company to temporarily suspend clinical trials of a drug for a rare genetic disorder until Dyax answers some questions about earlier animal tests.

"The issue is expected to be resolved in the next several weeks," Dyax said Tuesday. "We are committed to working with the FDA to resolve this issue as rapidly as possible," said Henry E. Blair, chairman and CEO of the Cambridge, Mass.-based biotechnology company.

Dyax said the FDA's action doesn't affect human testing. The company is in the midst of a Phase 2 clinical test, the second of three steps on the path to seeking FDA approval.

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Dyax shares lost $4.69, or 32.6%, to $9.72 in mid-morning trading. The stock dropped as low as $9.22. More than 6.2 million shares changed hands -- almost 30 times the daily average.

But the news didn't affect


( GENZ), Dyax's partner in developing the drug for the genetic disorder. Genzyme's stock added 20 cents to $42.28.

The FDA placed a "clinical hold" on the testing of DX-88, a treatment for hereditary angiodema, a rare genetic disorder that causes acute attacks of swelling in certain parts of the body such as the larynx, face, hands and feet.

Despite the clinical hold, Dyax said it still expects to release the results of the Phase 2 study in June.

Independent of its collaboration with Genzyme, Dyax is in the early stages of trying to develop DX-88 as a treatment of patients undergoing coronary artery bypass surgery. No clinical trials are being conducted.