Cambridge, UK: Horizon Discovery Group plc (LSE: HZD) (“Horizon”, “the Group” or “the Company”), a global leader in gene editing and gene modulation technologies, announces that Dr. Jonathan Milner is stepping down from his position as a Non-Executive Director of the Board with immediate effect.

Commenting on this announcement, Dr. Jonathan Milner said: “After 10 very enjoyable years on the Horizon Board I have decided to step down, to free more time to concentrate on my other interests. I have immensely liked working with the Horizon team, and would like to take this opportunity to thank my fellow Board members for such an enjoyable experience. From my initial meeting with the founders through to the IPO, and becoming a world leader in gene editing, I feel enormously privileged to have been a part of this exciting journey. I continue to be encouraged and enthusiastic about the growth prospects of Horizon’s business, and intend to remain a shareholder for the foreseeable future.”

Dr. Ian Gilham, Executive Chairman of the Board of Directors, Horizon Discovery, said: “We are sorry to see Jonathan depart, but completely understand his decision to prioritise other commitments. We are extremely grateful for his valuable insights as a member of Horizon’s Board over many years and wish him well in his future, not least as a considerable founding shareholder of the Horizon business.”

As of 15^th May 2018, Dr. Jonathan Milner owned a total of 10,815,172 ordinary shares of Horizon Discovery Group plc (7.25% of the Company’s issued share capital), and 20,888,110 ordinary shares of Abcam plc (10.21% of the Company’s issued share capital).

 Horizon’s Board consists of the following representatives:

 Dr Ian Gilham

Executive Chairman

Terry Pizzie

Chief Executive Officer

Richard Vellacott

Chief Financial Officer

Mrs Susan Searle

Non-Executive Director

Dr Susan Galbraith

Non-Executive Director

Dr Vishal Gulati

Non-Executive Director

Mr Grahame Cook

Non-Executive Director