PROSENSA HOLDING B.V. FILES REGISTRATION STATEMENT FOR PROPOSED INITIAL PUBLIC OFFERING

Leiden, the Netherlands—May 28, 2013—Prosensa Holding B.V., today announced that it has filed a registration statement on Friday May 24, 2013 on Form F-1 with the U.S. Securities and Exchange Commission (“SEC”) relating to the proposed initial public offering of its ordinary shares. The number of shares to be offered and the price range for the offering have not been determined.

J.P. Morgan and Citigroup are acting as joint book-running managers for the offering. Leerink Swann is acting as lead manager and Wedbush PacGrow Life Sciences and KBC Securities are acting as co-managers.

A registration statement relating to these securities has been filed with the SEC, but has not yet become effective. These securities may not be sold, nor may offers to buy be accepted, prior to the time the registration statement becomes effective. This press release shall not constitute an offer to sell or a solicitation of an offer to buy, 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.

The offering will be made only by means of a prospectus. When available, copies of the preliminary prospectus relating to the offering may be obtained from J.P. Morgan Securities LLC, c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, New York 11717; telephone: 866-803-9204; or Citigroup Global Markets Inc., c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, New York 11717, telephone: 1-800-831-9146 or email: batprospectusdept@citi.com.

–ENDS–

About Prosensa Holding B.V.

Prosensa is a Dutch biotechnology company engaged in the discovery and development of RNA-modulating therapeutics for the treatment of rare genetic disorders. Prosensa’s primary focus is on neuromuscular and neurodegenerative diseases with a large unmet medical need, including Duchenne muscular dystrophy, myotonic dystrophy and Huntington’s disease.

Contact:

Berndt Modig, CFO

Prosensa Holding B.V.

Phone: +31-71-3322100

Email: b.modig@prosensa.nl

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