CAMBRIDGE, Mass., Oct. 21, 2015 (GLOBE NEWSWIRE) — Dimension Therapeutics, Inc. (“Dimension” or the “Company”), a leading gene therapy company advancing novel, liver-directed treatments for diverse rare diseases, today announced the pricing of its initial public offering of 5,500,000 shares of its common stock at a public offering price of $13.00 per share. Dimension’s underwriters have been granted a 30-day option to purchase up to an additional 825,000 shares of common stock at the public offering price less underwriting discounts and commissions. All shares in the offering will be sold by Dimension and are expected to begin trading on the NASDAQ Global Select Market on October 22, 2015 under the symbol “DMTX”.

Goldman, Sachs & Co. and Citigroup Global Markets Inc. are acting as joint book-running managers and representatives of the underwriters for the offering. Wells Fargo Securities, LLC is acting as lead manager, and Canaccord Genuity Inc. and Cantor Fitzgerald & Co are acting as co-managers.

The offering is being made only by means of a prospectus. A copy of the final prospectus relating to these securities will be filed with the U.S. Securities and Exchange Commission (SEC). When available, copies of the prospectus relating to and describing the terms of the offering may be obtained from Goldman, Sachs & Co., Attention: Prospectus Department, 200 West Street, New York, New York 10282, or by telephone at (866) 471-2526, or e-mail at [email protected]; or Citigroup Inc., c/o Broadridge Financial Services, 1155 Long Island Avenue, Edgewood, NY 11717, or by telephone at (800) 831-9146, or by email at [email protected].

A registration statement relating to these securities was declared effective by the SEC on October 21, 2015. This press release shall not constitute an offer to sell or the solicitation of an offer to buy these securities, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

About Dimension Therapeutics

Dimension Therapeutics, Inc. is a leading gene therapy company focused on discovering and developing new therapeutic products for people living with devastating rare diseases associated with the liver and based on the most advanced adeno-associated virus (AAV) delivery technology. The company is advancing multiple programs toward clinical development, including: programs addressing unmet needs for patients suffering from OTC deficiency and GSDIa, a collaboration with Bayer HealthCare in hemophilia A, and a wholly owned program in hemophilia B. The company targets diseases with readily identifiable patient populations, highly predictive preclinical models, and well-described, and often clinically validated, biomarkers. Founded in 2013, Dimension maintains headquarters in Cambridge, Massachusetts.

CONTACT: Justin Jackson
         Burns McClellan, on behalf of Dimension Therapeutics
         212-213-0006, ext.327
         [email protected]