Methods and Compositions for Isolating Nucleic Acid Sequence Variants

A method of sorting a mixture of differentially tagged nucleic acid molecules according to the identity of their corresponding nucleotide tags, the method comprising:

• (i) contacting a nucleic acid sample comprising a mixture of differentially tagged nucleic acid molecules to a capture primer under hybridization conditions, wherein the capture primer is immobilized on a substrate and comprises a sequence complementary to a capture primer binding site in each of the differentially tagged nucleic acid molecules, whereby the differentially tagged nucleic acid molecules are immobilized;
• (ii) contacting the immobilized differentially tagged nucleic acid molecules to a polymerization primer under hybridization conditions, wherein the polymerization primer comprises a sequence complementary to a first unique region in the tag of one or more first nucleic acid molecules of the differentially tagged nucleic acid molecules, wherein the polymerization primer binds to the same strand of the one or more first nucleic acid molecules as the capture primer at a location that is 5′ to the capture primer;
• and
• (iii) isolating the one or more first nucleic acid molecules by contacting the immobilized differentially tagged nucleic acid molecules to a displacing nucleotide polymerase under nucleic acid polymerization conditions, wherein extension of the polymerization primer displaces the one or more first nucleic acid molecules from the immobilized capture primer;
• wherein the mixture of differentially tagged nucleic acid molecules are sorted according to the identity of their corresponding nucleotide tags.

A method of sorting a mixture of nucleic acid molecules according to the presence of a unique nucleotide sequence, the method comprising:

• (i) contacting a sample comprising a mixture of nucleic acid molecules to a capture primer under hybridization conditions, wherein the capture primer is immobilized on a substrate and comprises a sequence complementary to a capture primer binding site present in each of the nucleic acid molecules in the mixture, whereby the nucleic acid molecules in the mixture are immobilized;
• (ii) contacting the immobilized nucleic acid molecules to a polymerization primer under hybridization conditions, wherein the polymerization primer comprises a sequence complementary to a unique sequence present in one or more first nucleic acid molecules in the mixture, wherein the polymerization primer binds to the same strand of the one or more first nucleic acid molecules as the capture primer at a location that is 5′ to the capture primer;
• and
• (iii) isolating the one or more first nucleic acid molecules by contacting the immobilized nucleic acid molecules to a strand displacing nucleotide polymerase under nucleic acid polymerization conditions, wherein extension of the polymerization primer displaces the one or more first nucleic acid molecules from the immobilized capture primer;
• wherein the nucleic acid molecules are sorted according to the presence of the unique sequence.