Patent ID: 7135291

Claim:
A method for detecting the presence of a base substitution at a specific base in a target nucleic acid, the method comprising: (1) mixing a sample containing a target nucleic acid with a Nucleotide, wherein the Nucleotide (A) is modified at the 3′-terminus such that extension from the terminus by a DNA polymerase does not occur; (B) has a base sequence capable of annealing to a region containing a specific base in the target nucleic acid; and (C) contains a sequence in which if there is a mismatch between the specific base and a base corresponding to the specific base in the Nucleotide in a complex composed of the Nucleotide and the target nucleic acid, the Nucleotide is not cleaved with a nuclease, and if there is no mismatch between the specific base and a base corresponding to the specific base in the Nucleotide, the Nucleotide is cleaved with a nuclease to generate a new 3′-terminus; (2) treating the mixture with the nuclease and the DNA polymerase; and (3) detecting the presence of a base substitution at the specific base in the target nucleic acid based on the presence of cleavage of the Nucleotide with the nuclease and the presence of a DNA extension reaction subsequent to the cleavage.