The principle of T m-shift genotyping. In a multiplex reaction with two allele-specific primers and a common reverse primer, genomic DNA will be amplified by either one, or both, of the forward primers depending on which SNP alleles are present. Samples homozygous for one of the alleles will be amplified with the GC-tail primer and result in a melting curve that peaks in the high end of the temperature scale. Samples homozygous for the other allele will be amplified with the short allele-specific primer and give a melting curve with a peak at a lower temperature. Heterozygous samples will be amplified with both forward primers, and the melting curves will have two peaks.
