Abstract: The present invention provides improved compositions and methods of sequence detection and single nucleotide (“SNP”) genotyping. The methods of the present invention are related to combining sequence or allelic specific ligation on a solid phase platform with specific and efficient solid phase signal amplification. The methods for sequence detection include a first, second and third oligonucleotide. The methods of SNP genotyping include four oligonucleotides for SNPs associated with two alleles and additional oligonucleotides may be added for SNPs associated with more than two alleles. The usefulness of the present method is that it results in the determination of thousands of genotypes simply, rapidly and inexpensively on a solid support from a single genomic DNA sample.

Abstract: The present invention provides methods for determining the number of tandem repeat units in a region of double stranded DNA based on the use of RecA-like recombinase protein and oligonucleotide ligation. The methods of the present invention provide RecA coated, specific DNA oligonucleotide probes (RecA filaments) for homology searching in duplex DNA where the location of homologous sequences results in the formation of D-loop structures containing a duplex region comprising the oligonucleotide probe and one strand of the target DNA.

Abstract: A method for detecting a specific sequence, a mutation and/or a polymorphisms, including a single nucleotide polymorphism (SNP), is based on the use of RecA-like recombinase protein and primer extension (PE) or oligonucleotide ligation assays (OLA). RecA coated, specific DNA oligonucleotide probes (RecA filaments) are used for homology searching in duplex DNA. Location of homologous sequences results in the formation of D-loop or double D-loop structures containing a duplex regions comprising the oligonucleotide probe and one strand of the target DNA. In the case of the PE methods, probes are selected to terminate with their 3? end adjacent to the site of mutation or SNP such that a single nucleotide or terminator addition to the primer will be diagnostic of the mutation or SNP.

Abstract: A method for detecting mutations, such as a single base change or an addition or deletion of about one to four base pairs, is based on the use of an immobilized DNA mismatch-binding protein, such as MutS, which binds to a nucleic acid hybrid having a single base mismatch or unpaired base or bases, thereby allowing the detection of mutations involving as little as one base change in a nucleotide sequence. Such a method is useful for diagnosing a variety of important disease states or susceptibilities, including the presence of a mutated oncogene and the presence of DNA containing triplet repeat sequences which characterize several genetic diseases including fragile X syndrome. The present method is used to isolate or remove by affinity chromatography duplex DNA molecules containing mismatches such as error-containing molecules in PCR-amplified DNA samples. Methods for detecting and enriching minority sequences are disclosed.

Abstract: A method for detecting mutations, such as a single base change or an addition or deletion of about one to four base pairs, is based on the use of an immobilized DNA mismatch-binding protein, such as MutS, which binds to a nucleic acid hybrid having a single base mismatch or unpaired base or bases, thereby allowing the detection of mutations involving as little as one base change in a nucleotide sequence. Such a method is useful for diagnosing a variety of important disease states or susceptibilities, including the presence of a mutated oncogene and the presence of DNA containing triplet repeat sequences which characterize several genetic diseases including fragile X syndrome. The present method is used to isolate or remove by affinity chromatography duplex DNA molecules containing mismatches such as error-containing molecules in PCR-amplified DNA samples. Methods for detecting and enriching minority sequences are disclosed.

Abstract: A method for detecting mutations, such as a single base change or an addition or deletion of about one to four base pairs, is based on the use of an immobilized DNA mismatch-binding protein, such as MutS, which binds to a nucleic acid hybrid having a single base mismatch or unpaired base or bases, thereby allowing the detection of mutations involving as little as one base change in a nucleotide sequence. Such a method is useful for diagnosing a variety of important disease states or susceptibilities, including the presence of a mutated oncogene and the presence of DNA containing triplet repeat sequences which characterize several genetic diseases including fragile X syndrome. The present method is used to isolate or remove by affinity chromatography duplex DNA molecules containing mismatches such as error-containing molecules in PCR-amplified DNA samples. Also provided are compositions and kits useful for practicing the methods of the present invention.

Abstract: A method for detecting mutations, such as a single base change or an addition or deletion of about one to four base pairs, is based on the use of an immobilized DNA mismatch-binding protein, such as MutS, which binds to a nucleic acid hybrid having a single base mismatch or unpaired base or bases, thereby allowing the detection of mutations involving as little as one base change in a nucleotide sequence. Such a method is useful for diagnosing a variety of important disease states or susceptibilities, detecting the presence of a mutated oncogene and for isolating or removing by affinity chromatography duplex DNA molecules containing mismatches such as error-containing molecules in PCR-amplified DNA samples. Also provided are kits useful for practicing the methods of the present invention.