Annual Report and Notice of Annual General Meeting

HORIZON DISCOVERY GROUP PLC

("Horizon" or "the Company")

Annual Report and Notice of Annual General Meeting

Cambridge, UK, 2 June 2017: Horizon Discovery Group plc (LSE: HZD) ("Horizon" or "the Company"), the world leader in the application of gene editing technologies, announces that its annual report and accounts for the year ended 31 December 2016, which includes the notice convening the Company's 2017 Annual General Meeting (AGM), has been posted to shareholders.

The annual report and accounts and 2017 notice of AGM are available on the Investor Relations section of the Company's website at www.horizondiscovery.com.

Horizon also announces that its 2017 AGM will be held on Wednesday, 28 June 2017. The meeting will be held at the Company's offices - Building 8100 Cambridge Research Park, Waterbeach, Cambridge, CB25 9TL, commencing at 10.00am.

ENDS

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

Numis Securities Limited (Broker and NOMAD)

Michael Meade / Freddie Barnfield

Tel: +44 (0) 207 260 1000

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]

Zyme Communications (Trade and Regional Media)

Katie Odgaard

Tel: +44 (0)7787 502 947

Email: [email protected]

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, CRISPR and Transposon) 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 over 1,600 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".