Director/PDMR Shareholding

Horizon Discovery Group plc

("Horizon" or the "Company")

Directorate Shareholding

Cambridge, UK, 6 November 2015: Horizon Discovery Group plc (LSE: HZD), the international life science company supplying research tools and services that power genomics research and the development of personalised medicines, announces that, further to the announcement made on 7 October 2015, following the issue of Deferred Consideration Shares to former stockholders of Sage, Mr David Smoller, a Director of the Company, received 48,539 Deferred Consideration Shares on 8 October 2015 for nil cost, and consequently his direct beneficial interest in the Company is 760,879 ordinary shares, representing 0.81% of the total issued share capital of the Company.

ENDS

Note: all defined terms in the announcement of 7 October 2015 ("Issue of Equity") are applicable to this announcement

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

Zyme Communications (Trade and Regional Media)

Katie Odgaard

Tel: +44 (0)7787 502 947

Email: [email protected]

Consilium Strategic Communications (Financial Media and Investor Relations)

Amber Fennell / Jessica Hodgson / Matthew Neal / Laura Thornton

Tel: +44 (0) 20 3709 5701

Email: [email protected]

Panmure Gordon & Co. (NOMAD and Broker)

Corporate Finance: Freddy Crossley / Fabien Holler / Duncan Monteith

Broking: Tom Salvesen

Tel: +44 20 7886 2500

Notes for Editors

About Horizon Discovery Group plc www.horizondiscovery.com/

Horizon is a revenue-generating life science group supplying research tools to organizations engaged in translational genomics research and the development of personalized medicines. Horizon has a diverse and international customer base of over 1,200 organizations across more than 50 countries, including major pharmaceutical, biotechnology and diagnostic companies as well as leading academic research centers. The Group supplies its products and services into multiple markets, estimated to total in excess of £29 billion by 2015.

Horizon's core capabilities are built around its proprietary translational genomics platform, a high-precision and flexible suite of gene editing tools able to alter almost any endogenous gene sequence of human or mammalian cell-lines. Horizon offers over 20,000 catalogue products, almost all of which are based on the application of gene editing to generate cell lines that accurately model the disease-causing mutations found in genetically based diseases. These 'patients-in-a-test-tube' are being used by customers to identify the effect of individual or compound genetic mutations on drug activity, patient responsiveness, and resistance, which may lead to the successful prediction of which patient sub-groups will respond to currently available and future drug treatments.

In addition, Horizon provides custom cell line and in vivo model generation services for research and bioproduction applications, quantitative molecular reference standards, in vivo disease models, and contract research and custom screening services.

Horizon is headquartered in Cambridge, UK, and is listed on the London Stock Exchange's AIM market under the ticker "HZD", for further information please visit: www.horizondiscovery.com.