Annual Report and Notice of Annual General Meeting

Horizon Discovery Group plc

("Horizon" or "the Company" or "the Group")

Annual Report and Notice of Annual General Meeting

Cambridge, UK, 17 May 2018: Horizon Discovery Group plc (LSE: HZD), a global leader in gene editing and gene modulation technologies, announces that its annual report and accounts for the year ended 31 December 2017, which includes the notice convening the Company's 2018 Annual General Meeting (AGM), has been posted to shareholders.

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

The AGM will be held on Monday, 18 June 2018 and take place at the Company's offices - Building 8100 Cambridge Research Park, Waterbeach, Cambridge, CB25 9TL, commencing at 12.00 noon.

ENDS

For further information, please contact:

Horizon Discovery Group plc

Ian Gilham, Executive Chairman

Terry Pizzie, Chief Executive Officer

Richard Vellacott, Chief Financial Officer

Tel: +44 (0) 1223 655 580

Consilium Strategic Communications (Financial Media and Investor Relations)

Mary-Jane Elliott / Matthew Neal / Melissa Gardiner

Tel: +44 (0) 20 3709 5701

Email: [email protected]

Numis Securities Limited (Broker and NOMAD)

Michael Meade / Freddie Barnfield

Tel: +44 (0) 207 260 1000

About Horizon Discovery Group plc www.horizondiscovery.com

Horizon Discovery Group plc (LSE: HZD) ("Horizon") is a world leader in gene editing and gene modulation technologies. Horizon delivers inspired cell solutions using its translational genomics platform, a highly precise and flexible suite of DNA editing (rAAV, ZFN, CRISPR and Transposon) and modulation (RNAi, cDNA and ORF) tools for research and clinical applications that advance human health. Horizon's platforms and capabilities enable researchers to alter almost any gene or modulate its function in human or mammalian cell lines.

Horizon offers an extensive range of catalogue products and related research services to support a greater understanding of the function of genes across all species and the genetic drivers of human disease and the development of personalized molecular, cell and gene therapies. These have been adopted by over 10,000 academic, drug discovery, drug manufacturing and clinical diagnostics customers around the globe, as well as in the Company's own R&D pipeline.

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