Patent ID: 8586299

Claim:
A method of allele-specific amplification of a variant of a target sequence, which exists in the form of several variant sequences, comprising (a) providing a sample, possibly containing at least one variant of a target sequence; (b) providing a first oligonucleotide, at least partially complementary to one or more variants of the target sequence; (c) providing a second oligonucleotide, at least partially complementary to one or more variants of the target sequence, having a 3′-terminal nucleotide complementary to only one variant of the target sequence; wherein said second oligonucleotide incorporates at least one nucleotide with a base covalently modified at the exocyclic amino group; (d) providing conditions suitable for the hybridization of said first and second oligonucleotides to at least one variant of the target sequence; and (e) providing conditions suitable for the oligonucleotide extension by a nucleotide-incorporating biocatalyst; wherein said biocatalyst is capable of extending said second oligonucleotide when it is hybridized to the variant of the target sequence for which it has said complementary 3′-terminal nucleotide, and substantially less when said second oligonucleotide is hybridized to the variant of the target sequence for which it has a non-complementary 3′-terminal nucleotide.