Patent ID: 7935480

Claim:
A method for detecting a mutation in a target nucleic acid sequence in a sample, the target nucleic acid sequence comprising a first DNA strand and optionally the complementary strand thereof, said method comprising: (a) adding a detection primer to the nucleic acid, wherein the detection primer binds to the first DNA strand at a DNA sequence that comprises the mutation site, wherein the detection primer is capable of binding to said DNA sequence and being extended regardless of whether or not there is a mutation at the mutation site; (b) extending the detection primer to form second DNA strands that are complementary to the first DNA strand; (c) adding an amplification primer to the nucleic acid, wherein the amplification primer binds to the second DNA strand and/or to the complementary strand, at a position away from the mutation site; (d) extending the amplification primer to form third DNA strands that are complementary to the second DNA strands, and/or additional copies of the first DNA strand; (e) annealing the DNA strands by complementary base pairing, to form nucleic acid duplexes, wherein if the two strands of the duplex have a mismatched residue at the mutation site, the duplex is a heteroduplex, and wherein if the two strands of the duplex do not have a mismatched residue at the mutation site, the duplex is a homoduplex; and (f) detecting the presence of heteroduplexes and/or homoduplexes.