Issue of Equity

Horizon Discovery Group plc

Issue of Equity

Cambridge, UK, 31 January 2017: Horizon Discovery Group plc (LSE: HZD) ("Horizon" or the "Company"), the world leader in the application of gene editing technologies, today announces that, further to the announcement made on 8 January 2015, the conditions for the issue of additional new ordinary shares of 1p each in the Company to former shareholders of Haplogen Genomics GmbH ("Haplogen") pursuant to a Sale and Purchase Agreement dated 7 January 2015 (the "Sale and Purchase Agreement") have been satisfied. This represents the final consideration payable in respect of the acquisition of Haplogen.

Horizon has approved the allotment and issue of 857,971 new ordinary shares of 1p each in the Company (the "Second Earn-Out Shares") to the former shareholders of Haplogen under the Sale and Purchase Agreement, and an application has been made for the admission to trading on AIM of the Second Earn Out Shares ("Admission"). Admission is expected to take place on or about 3 February 2017. The Second Earn Out Shares will rank pari passu in all respects with Horizon's existing shares in issue.

Following Admission, the Company's enlarged issued share capital will comprise 96,136,838 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 96,136,838. This figure of 96,136,838 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 in their interest in, the share capital of the Company under the FCA's Disclosure and Transparency Rules.

ENDS

Notes for Editors:

For further information from Horizon Discovery Group plc, please contact:

Horizon Discovery Group plc

Darrin Disley, Chief Executive Officer

Richard Vellacott, Chief Financial Officer

Chris Claxton, VP Investor Relations

Tel: +44 (0) 1223 655 580

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 in vivo 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 Group'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".