From our experience, the spacing of the allele clusters in Figures 8 and 9 are comparable or better than those scatter plots observed in other methods (2, 26, 27) . The exquisite specificity achieved with the Endo IV enzyme, combined with the shorter probes used and the high signal accumulation, gives this assay an advantage over other SNP assays. In comparison with other signal accumulating assays (2), the Endo IV assay has similar levels of high signal accumulation, but uses shorter probes with higher specificity than those assays. In the case of hybridization-based assays (5, 25) , the Endo IV assay has not only a signal accumulation advantage, but also uses shorter probes with a specificity advantage. In addition, the shorter probes allow much more flexibility in assay design compared to other methods with longer probes.