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The use of Short Tandem Repeats (STR) has been utilized as a means of examining biological evidence in the Forensic community for the past few years. Each of the STR loci evaluated by our laboratory are composed of 3-7 base pair repeats and can be amplified using the Polymerase Chain Reaction (PCR). Because of the small size of the STR alleles (usually less than 350bp) they are useful in the analysis of small or degraded samples which are frequently encountered in Forensic casework. The ability to simultaneously amplify several STR loci in a single amplification reaction allows an analyst to obtain multi-allelic information and hence, greater discrimination, from a very small amount of DNA.

We have examined two new Forensic multiplex systems. The first to be presented here (designated as FTP3) combines the STR loci vWA, FES/FPS and CSF. The loci in FTP3 are on chromosome 12, 15, and 5 respectively and the variation in the number of alleles ranges from 8 to 11 alleles per locus. The second (designated as FMP4) combines the STR loci D5S818, D7S820 and F13A1 with the AmpFLP D1S80. The loci in FMP4 are on chromosome 5, 7, 6 and 1 respectively and the variation in the number of the STR alleles ranges from 9 to 14 alleles per locus. The product size of each of the multiplexed STR loci fall into three (3) non-overlapping size ranges and are separated using a 9% tris-sulfate polyacrylamide gel and visualized by SYBRÔ Green fluorescent staining. Results of the validation studies for FTP3 and FMP4 will be presented.