** Shares of surgical device maker Axogen AXGN.O fall 20% to $13 premarket

** The U.S. FDA has extended the review period for company's marketing application for Avance Nerve Graft — a surgically implanted device made from human nerve tissue used to repair damaged peripheral nerves — by three months to December 5

** The extension was prompted by Axogen's submission of substantial new manufacturing and facility information, which the FDA classified as a "major amendment"

** A major amendment designation allows the FDA additional time to review the new data under its guidelines

** Company is seeking approval to transition Avance Nerve Graft from a tissue product to a biologic

** Shares down 1.3% YTD, up to last close

(Reporting by Kamal Choudhury in Bengaluru)

((Kamal.Choudhury@thomsonreuters.com))