ID2 and ocular melanoma: [13], [14]. As few as three genes (PHLDA1, FZD6 and ENPP2) correctly predicted the class of all tumor samples. Inhibitor of DNA binding 2, ID2, down regulated in class-2 (i.e. high-risk) tumors, was later reported by the same authors as the top class discriminating gene [14], the loss of which causes an increase in the rate of liver metastasis in a transgenic mouse model of ocular melanoma [15]. More recently, the usage of a 15-gene PCR-based assay has been proposed as a suitable method for the routine identification of the high-risk phenotype [16].