Abstract: A method for increasing oligonucleotide selectivity comprising reversibly binding two oligonucleotides at adjacent positions to the bases on a complementary template and then spontaneously and irreversibly covalently joining said oligomers via two reactive groups brought into proximity of each other by the binding of the oligonucleotides, in the absence of added reagent or enzyme. By using a shorter, lower affinity, highly selective first oligonucleotide complementary which binds to the site of a point mutation combined, with a longer, high affinity, less selective second oligonucleotide, this method provides an effective way to identify the presence of absence of a point mutation.