Marco A. Scarpetta, PhD and Stefanie A. Turek
Detroit Police Crime Laboratory
The AmpliFLP D1S80 PCR Amplification Kit is being validated for forensic casework in the Detroit Police Crime Lab by performing a subset of the experiments described in the TWGDAM guidelines. D1S80 amplification products are analyzed using the GeneAmp Detection Gel High Resolution Gel Concentrate and Loading Buffer Kit (Perkin-Elmer) followed by staining with SYBR Green I (FMC Bioproducts). A population database study was conducted, in which 150 individuals were typed from each of the three major racial groups (Black, Caucasian and Hispanic). Allele and genotype frequencies were determined for each racial group, and the genotype frequencies show Hardy-Weinberg Equilibrium. Furthermore, no linkage was observed between the D1S80, HLA-DQa and Polymarker loci for the individuals tested in our database sample. DNA extracted from two individuals was mixed in defined ratios before amplification to determine the limits of detection for mixed samples. Correct types of both individuals were called even when the minor contributor was 10% of the total input DNA. Finally, the recommended silver staining protocol has been replaced with SYBR Green post-staining of acrylamide gels. Therefore, a D1S80 gel was stained and photographed with both SYBR Green and silver staining to verify that there are no differences in the observed alleles.
Several studies remain to be completed. To ascertain the validity of the results obtained, a concordance study is being run with a group at NIST studying the D1S80 locus. D1S80 types obtained from blood, semen and buccal scrapings from the same individual will be obtained to check that the same type is seen from any bodily fluid. Blood stains will be subjected to a variety of environmental insults designed to mimic actual evidentiary material, followed by typing of the samples to detect which varieties of contaminants could inhibit amplification. An adjudicated case has been sent to Roche LabCorp to verify that the D1S80 type will still include the suspect. Finally, a set of NIST standards (SRM 2391) will be typed as a proficiency test.
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