Discrimination method of target base in DNA, and allele specific primer used in the method of the same

A method for discriminating a target base carried by a target DNA, comprising:

• (1) a DNA elongation step comprising
• (a) binding to said target DNA a test allele specific primer,
• wherein said target DNA comprises the sequence 3′-(G-G-S1)-5′, S1 being the target base, and
• wherein said test allele specific primer comprises the sequence 5′-(B3-B2-S1′)-3′, (B3, B2) being bases selected from the group consisting of (T, T), (T, G), (G, T), and (G, G), wherein S1′ is the 3′ terminal base of the test allele specific primer and is complimentary to the base predicted to be S1;
• and
• (b) causing a test DNA elongation reaction;
• and
• (2) a discrimination step comprising measuring the efficiency of said DNA elongation to discriminate that said target is the same as said predicted base when the efficiency is high, or that said target base is distinct from said predicted base that said target base is distinct from said predicted base.