Nibedita Mahanti, Stephen Milligan, Heather Spillane, Dorothy Martus, Kathy Kuebler, Lynne Helton, Don Yet, Paul Donald and Charles Barna
Michigan State Police DNA Laboratory, East Lansing, MI

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STR (short tandem repeats) have gained global recognition as a highly informative approach to human identification in the forensic community. Recently, Promega Corporation has introduced an octaplex, PowerPlex^tm , made up of D16S539, D7S820, D13SS317, D5S818, CSF1PO, TPOX, TH01, and vWA, using fluorescently tagged primers. Each of these loci are true tetranucleotide repeats. Only two microvariants have been reported, each occurring at the TH01 locus. The P_D of this genetic system is estimated to be approximately 1 in 100,000,000 in Caucasian-Americans and expected to be 10-20 times greater in African-Americans⁴, making this an attractive system for use in forensic casework and convicted offender databases.

Currently, the Michigan State Police DNA laboratory is evaluating this PowerPlex^tm using the Hitachi FMBIO^® fluorescent scanner. This initial report, using the manufacturer’s recommended procedure, is a sensitivity study varying the amount of target DNA in the amplification cocktail. The following criteria will be used to monitor the experiment: 1) Balance at each locus. 2) Allele dropout. 3) Stutter bands. This initial study indicates the optimum input target DNA is 1-4 ng.