Published: May 13, 2010 4:39 PM EDT

 WASHINGTON (AP) - The largest U.S. drugstore chain, Walgreen Co., says it is holding off selling genetic testing kits at its stores after the Food and Drug Administration raised concerns with the kits' manufacturer.

Pathway Genomics had said that its saliva swab would be on Walgreen's shelves later this month. It says consumers can use the kits to determine if they have a predisposition for chronic diseases or might have a response to a common drug.

But the FDA wrote a letter to Pathway suggesting the company has not received federal approval to sell the kit, which the agency considers a medical device.

A Walgreen spokesman said Wednesday the company decided to wait until the outcome of the discussions between Pathway and the FDA before stocking the kits.

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