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Detection of nucleic acid differences using combined endonuclease cleavage and ligation reactions

  • US 7,198,894 B2
  • Filed: 11/30/2001
  • Issued: 04/03/2007
  • Est. Priority Date: 12/01/2000
  • Status: Expired due to Term
First Claim
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1. A method for identifying a mutant nucleic acid sequence differing by one or more single-base changes, insertions, or deletions, from a normal target nucleotide sequences, said method comprising:

  • providing a sample potentially containing the normal target nucleotide sequence as well as the mutant nucleic acid sequence;

    providing two labeled oligonucleotide primers suitable for hybridization on complementary strands of the target nucleotide sequence and the mutant nucleic acid sequence;

    providing a polymerase;

    blending the sample, the labeled oligonucleotide primers, and the polymerase to form a polymerase chain reaction mixture;

    subjecting the polymerase chain reaction mixture to one or more polymerase chain reaction cycles comprising a hybridization treatment, wherein oligonucleotide primers hybridize to the target nucleotide sequence and/or the mutant nucleic acid sequence, an extension treatment, wherein the hybridized oligonucleotide primer is extended to form an extension product complementary to the target nucleotide sequence and/or the mutant nucleic acid sequence to which the oligonucleotide primer is hybridized, and a denaturation treatment, wherein hybridized nucleic acid sequences are separated;

    inactivating the polymerase;

    denaturing the polymerase chain reaction extension products;

    annealing the polymerase chain reaction extension products to form heteroduplexed products potentially containing the normal target nucleotide sequence and the mutant nucleic acid sequence;

    providing an endonuclease which preferentially nicks or cleaves heteroduplexed DNA at a location one base away from mismatched base pairs;

    blending the heteroduplexed products and the endonuclease to form an endonuclease cleavage reaction mixture;

    incubating the endonuclease cleavage reaction mixture so that the endonuclease preferentially nicks or cleaves heteroduplexed products at a location one base away from mismatched base pairs;

    providing a ligase;

    blending the potentially nicked or cleaved heteroduplexed products and the ligase to form a ligase resealing reaction mixture;

    incubating the ligase resealing reaction mixture to seal the nicked heteroduplexed products at perfectly matched base pairs but with substantially no resealing of nicked heteroduplexed products at locations adjacent to mismatched base pairs;

    separating products resulting from said incubating the ligase resealing reaction mixture by size or electrophoretic mobility; and

    detecting the presence of the normal target nucleotide sequence and the mutant nucleic acid sequence in the sample by distinguishing the separated products resulting from said incubating the ligase resealing reaction mixture.

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