Exhibit 99.7
To be posted on LinkedIn, Twitter

Today bluebird bio announced a definitive agreement to be acquired by Carlyle and SK Capital. Read more in our press release: [insert link]
ADDITIONAL INFORMATION AND WHERE TO FIND IT
The tender offer for the outstanding shares of bluebird bio referenced in this communication has not yet commenced. This communication is not an offer to buy nor a solicitation of an offer to sell any securities of bluebird bio. The solicitation and the offer to buy shares of bluebird bio common stock will only be made pursuant to a Tender Offer Statement on Schedule TO, including an offer to purchase, a letter of transmittal and other related materials that Beacon Parent Holdings, L.P. (“Parent”) and Beacon Merger Sub, Inc. (“Merger Sub”) intend to file with the Securities and Exchange Commission. In addition, bluebird bio will file with the SEC a Solicitation/Recommendation Statement on Schedule 14D-9 with respect to the tender offer. Once filed, investors will be able to obtain a free copy of these materials and other documents filed by Parent, Merger Sub and bluebird bio with the SEC at the website maintained by the SEC at www.sec.gov. Investors may also obtain, at no charge, any such documents filed with or furnished to the SEC by bluebird bio under the “investors & media” section of bluebird bio’s website at www.bluebirdbio.com.
INVESTORS AND SECURITY HOLDERS ARE ADVISED TO READ THESE DOCUMENTS WHEN THEY BECOME AVAILABLE, INCLUDING THE SOLICITATION/RECOMMENDATION STATEMENT ON SCHEDULE 14D-9 OF BLUEBIRD BIO AND ANY AMENDMENTS THERETO, AS WELL AS ANY OTHER DOCUMENTS RELATING TO THE TENDER OFFER AND THE MERGER THAT ARE FILED WITH THE SEC, CAREFULLY AND IN THEIR ENTIRETY PRIOR TO MAKING ANY DECISIONS WITH RESPECT TO WHETHER TO TENDER THEIR SHARES INTO THE TENDER OFFER BECAUSE THEY CONTAIN IMPORTANT INFORMATION, INCLUDING THE TERMS AND CONDITIONS OF THE TENDER OFFER.
Forward-Looking Statements
The statements included above that are not a description of historical facts are forward-looking statements. Words or phrases such as “believe,” “may,” “could,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “seek,” “plan,” “expect,” “should,” “would” or similar expressions are intended to identify forward-looking statements. The forward-looking statements are based on bluebird bio’s current beliefs and expectations and include, but are not limited to: statements regarding beliefs about the potential benefits of the transaction; the planned completion and timing of the transactions contemplated by the Merger Agreement; and the prospective performance and outlook of the surviving company’s business, performance, and opportunities. Risks and uncertainties that could cause results to differ from expectations include: uncertainties as to the timing and