tse TSE was used to determine the exact mutations present. TSE requires TiTaq, diGTP-biotin, and extenders that contain 3Ј target-specific bases and 5Ј codes specific for the EraCode beads described above. During TSE, TiTaq incorporates labels on extenders only when specific targets having 5Ј iCs are present. The nonnatural base pair formed by iG and iC has been successfully used for both molecular recognition (13) (14) (15) and for site-specific enzymatic incorporation (16 -18 ) . To date, we have covalently coupled a series of different reporter groups to diGTP, using succinimidyl ester chemistry and confirmed enzymatic incorporation into nucleic acids by use of several commercially available polymerases (data beyond the scope of this report). In many cases, single amplicons spanning regions that incorporated multiple mutations were used as templates for multiple extenders. After TSE, EraCode-labeled beads and streptavidin-phycoerythrin were added, and the reactions were analyzed on the Luminex 100 . Data are reported in median fluorescence intensity (MFI).