sequencing technique initially discussed above this is due to the ability of dna polymerase from thermus aquaticus to catalyse a non template mediated addition of a deoxyribonucleotide to the 3 u2032 hydroxyl of pcr products this is generally known as the u201c n 1 u201d product and can be generated in preference to the u201c n u201d product the results reported here however refer to the u201c n u201d product rather than the u201c n 1 u201d product for which the labelled primer pcr conditions have been optimised to produce the products of the amplification process for each locus were then diluted mixed with one another and reanalysed to produce a single ladder for each loci having even peak heights an initial level of 1000 arbitary units au was increased to 1000 5000 au to give greater signal strength and volume for the ladder the single ladders produced in this way were then mixed together to give the cocktail discussed above the proportions of each ladder used are controlled to give balanced peak areas the cocktail was then validated using applied biosystems 373a and applied biosystems 377 automated sequencers with genescan and genotyper software allelic ladders according to the invention can be prepared by applying pcr amplification techniques to a pre existing sample of the allelic ladder mixture alternatively the allelic ladders can be constructed from the sequence information provided herein the new ladders disclosed above significantly extends the range of alleles which can be identified in any dna profiling system the allelic ladder mixture is used as a control sample alongside samples from.