// Peter Johansson 1 , Lauren G. Aoude 1 , Karin Wadt 2 , William J. Glasson 3 , Sunil K. Warrier 3 , Alex W. Hewitt 4, 5 , Jens Folke Kiilgaard 6 , Steffen Heegaard 6, 7 , Tim Isaacs 5 , Maria Franchina 5 , Christian Ingvar 8 , Tersia Vermeulen 9 , Kevin J. Whitehead 10 , Christopher W. Schmidt 1 , Jane M. Palmer 1 , Judith Symmons 1 , Anne-Marie Gerdes 2 , Göran Jönsson 8 , Nicholas K. Hayward 1 1 QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia 2 Department of Clinical Genetics, Rigshospitalet, Copenhagen, Denmark 3 The Terrace Eye Centre, Brisbane, QLD, Australia 4 Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia 5 Lions Eye Institute, University of Western Australia, Perth, WA, Australia 6 Department of Ophthalmology, Rigshospitalet-Glostrup Hospital, University of Copenhagen, Copenhagen, Denmark 7 Department of Pathology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark 8 Department of Clinical Sciences, Lund University, Lund, Sweden 9 The Royal Perth Hospital, Perth, WA, Australia 10 Sullivan Nicolaides Pathology, Brisbane, QLD, Australia Correspondence to: Peter Johansson, e-mail: Peter.Johansson@qimrberghofer.edu.au Keywords: uveal melanoma, recurrent mutation, PLCB4, copy number variation, structural variants Received: September 14, 2015 Accepted: November 26, 2015 Published: December 14, 2015 ABSTRACT Next generation sequencing of uveal melanoma (UM) samples has identified a number of recurrent oncogenic or loss-of-function mutations in key driver genes including: GNAQ , GNA11 , EIF1AX , SF3B1 and BAP1 . To search for additional driver mutations in this tumor type we carried out whole-genome or whole-exome sequencing of 28 tumors or primary cell lines. These samples have a low mutation burden, with a mean of 10.6 protein changing mutations per sample (range 0 to 53). As expected for these sun-shielded melanomas the mutation spectrum was not consistent with an ultraviolet radiation signature, instead, a BRCA mutation signature predominated. In addition to mutations in the known UM driver genes, we found a recurrent mutation in PLCB4 (c.G1888T, p.D630Y, NM_000933), which was validated using Sanger sequencing. The identical mutation was also found in published UM sequence data (1 of 56 tumors), supporting its role as a novel driver mutation in UM. PLCB4 p.D630Y mutations are mutually exclusive with mutations in GNA11 and GNAQ , consistent with PLCB4 being the canonical downstream target of the former gene products. Taken together these data suggest that the PLCB4 hotspot mutation is similarly a gain-of-function mutation leading to activation of the same signaling pathway, promoting UM tumorigenesis.