In a restrict number of UM patients, there are tumour initiating mutations in CYSLTR2 (cysteinyl leukotriene receptor 2), which also encodes a G-protein coupled receptor (Figure 1) [61,62], or PLCB4 (1-Phosphatidylinositol-4,5-bisphosphate phosphodiesterase beta-4), which encodes a protein downstream in the GNAQ signalling cascade (Figure 1) [63]. The gene discussed is CYSLTR2; the disease is neoplasm.