Pre-heating samples to improve PCR amplification efficiency. This graph plots the test:reference product ratio generated by PRT assay ‘2n13’ (Y-axis), amplicon sizes 729 bp and 355 bp, against temperatures used to pre-heat the input genomic DNAs (X-axis). After heating, samples were snap cooled on ice before adding them to the PRT reaction mix. Each condition was run on 2–4 samples in duplicate, and maximum and minimum ratios are plotted as error bars. The ‘Control’ ratio at the start of the chart indicates the ratio produced by amplifying non-heated input DNA, and the dotted horizontal line at 1.43 indicates the ratio that would be produced if the slightly different sized test and reference amplicons amplified with exactly equal efficiency.