Nucleic acid amplification

A method for detecting a variant nucleotide sequence, the method comprising selectively amplifying a target nucleotide sequence located within a nucleic acid molecule and comprising the variant sequence, wherein the method comprises:

• contacting the nucleic acid molecule (“template” molecule) with
• (i) at least one facilitator oligonucleotide, wherein the facilitator oligonucleotide includes at least one modification at or near its 3′ terminus such that 3′ extension from the facilitator oligonucleotide is blocked, and
• (ii) two or more oligonucleotide primers, at least one of which is an initiator primer modified such that the presence of the modification prematurely terminates complementary strand synthesis,
• wherein the facilitator oligonucleotide and the initiator primer bind to substantially the same or adjacent regions of the template nucleic acid molecule and the facilitator oligonucleotide further comprises 3′ sequences complementary to the target sequence 3′ to the binding location of the initiator primer and wherein said 3′ sequences enable preferential binding of the facilitator oligonucleotide to the target nucleotide sequence comprising the variant sequence rather than to corresponding nonvariant sequence;
• carrying out thermocyclic, enzymatic amplification such that the specific target sequence is selectively amplified;
• and
• comparing the nucleotide sequence of the amplified product with a sequence corresponding to the nonvariant target sequence, to detect the variant nucleotide sequence.