** Shares in gene therapy co Bluebird Bio BLUE.O up 11% at $4.54 in after-the-bell trading after it confirmed receipt of unsolicited buyout offer from Ayrmid Ltd for $4.50/share cash upfront, one-time contingent value right of $6.84/shr payable if it reaches a net sales milestone

** BLUE shares had ended Friday's regular trading up 7.7% at $4.08 after spiking to $4.43 session high in a volume jump minutes before the close

** It fell 42% on Feb 21 after it accepted a discounted deal with PE firms Carlyle and SK Capital Partners. Under the agreed deal BLUE would be taken private for $3.00/shr cash, one-time contingent value right of $6.84/shr payable on hitting a net sales milestone

** BLUE, which had closed at $7.04 on Feb 20, forged the private equity deal after a prolonged struggle to survive a cash crunch in a difficult market environment

** BLUE says previously talked with privately-held UK company Ayrmid as part of a review of strategic alternatives but Ayrmid had not submitted any proposal as part of that process

** BLUE says reviewing the Ayrmid proposal but remains subject to the terms of the Carlyle/ SK deal and its Board has not changed its recommendation in support of the Merger

** At its peak BLUE had traded above $3,000 in March 2018.

(Reporting By Sinéad Carew)

((sinead.carew@thomsonreuters.com; +13322191897;))