Additional Listing

21 April 2017

Horizon Discovery Group plc 

Additional Listing

The Company has issued and allotted 100,000 new ordinary shares of 1p each pursuant to the exercise of options.

Accordingly, an application has been made for 100,000 new ordinary shares to be admitted to trading on AIM and it is expected that admission will take place on 25 April 2017.

The new ordinary shares will rank pari passu with the existing shares of the Company.

Following Admission, the Company's enlarged issued share capital will comprise 96,259,340 ordinary shares with one voting right per share. No shares are held in Treasury. The total number of voting rights in the Company is therefore 96,259,340.

This figure of 96,259,340 ordinary shares may be used by shareholders in the Company as the denominator for the calculations by which they will determine if they are required to notify their interest in, or a change to their interest in, the share capital of the Company under the FCA's Disclosure and Transparency Rules.

For further information, please contact:

Consilium Strategic Communications (Financial Media and Investor Relations)

Mary-Jane Elliott / Susan Stuart / Matthew Neal / Melissa Gardiner

Tel: +44 (0) 20 3709 5701

Email: [email protected]

Numis Securities Limited (Joint Broker and NOMAD)

Michael Meade / Freddie Barnfield

Tel: +44 (0) 207 260 1000

RBC Capital Markets (Joint Broker)

Paul Tomasic / Marcus Jackson

Tel: +44 (0) 20 7653 4000

About Horizon Discovery Group plc www.horizondiscovery.com/

Horizon Discovery Group plc (LSE: HZD) ("Horizon"), is a world-leading gene editing company that designs and engineers genetically-modified cells and then applies them in research and clinical applications that advance human health.

Horizon's core capabilities are built around its proprietary translational genomics platform, a highly precise and flexible suite of gene editing tools (rAAV, ZFN and CRISPR) able to alter almost any gene sequence in human or mammalian cell-lines.

Horizon offers over 23,000 catalogue products and related research services, almost all of which are based on the generation and application of cell and animal models that accurately recapitulate the disease-causing genetic anomalies found in diseases like cancer. Horizon's commercial offering has been adopted by c1,600 unique research organisations in over 50 countries as well as in the Company's own R&D pipeline to support: a greater understanding of the genetic drivers of disease and the development of molecular, cell and gene therapies that can be prescribed on a personalised basis.

Horizon is headquartered in Cambridge, UK, and is listed on the London Stock Exchange's AIM market under the ticker "HZD".