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SWGDAM Developmental Validation of a 19-Locus Y-STR System for Forensic Casework

NCJ Number
Date Published
January 2004
16 pages
Jack Ballantyne, Darlene L. Daniels, Ashley M. Hall
A Scientific Working Group on DNA Analysis Methods (SWGDAM) conducted a developmental validation study on two Y-STR multiplex systems (MPI and MPII) that collectively permit the co-amplification of 19 Y-STR markers.
The markers are DYS393, DYS392, DYS391, DYS3891, DYS389II, Y-GATA-A7.2 (DYS461), DYS438, DYS385a, and DYS385b(MPI); DYS425, DYS388, DYS390, DYS439, DYS434, DYS437, Y-GATA-C.4, Y-GATA-A7.1(DYS460), Y-GATA-H.4, and DYS19(MPII). Performance checks subsequent to PCR parameter optimization indicated that MPI and MPII are suitably reproducible, precise, and accurate for forensic use. The sensitivity of the systems is such that a full 19-locus Y-STR profile was obtainable with 150-200 pg of male DNA, and some loci were detectable even with as little as 20-30 pg of input DNA. Primate specificity was demonstrated by the lack of cross-reactivity with a variety of commonly encountered bacterial and animal species, with the single exception of a monomorphic canine product that was outside of the size range of human alleles from any of the 19 loci. The authors previously demonstrated that female nonhuman primate DNA (gorilla and lemur) produces MPI or MPII allelic signals; however, these were clearly distinguishable from the human female products. Only three of the 19 MPI and MPII loci, DYS392 and DYS385 (a,b) were found to be affected by the presence of large quantities of female DNA in the absence of competing male DNA. The mixture studies involved male/female DNA mixtures and male/male DNA mixtures. In order to assess the performance of MPI and MPII with specimens commonly encountered in forensic casework, a variety of sample types were tested, including a neat semen stain from a vasectomized individual, a series of admixed male/female bloodstains, a 24-h post-coital cervicovaginal swab, the non-sperm (female) fraction of a 48-h post-coital swab from a differential extraction, and a semen stain on a pair of panties from a rape victim. 2 tables, 7 figures, and 22 references
Date Created: December 30, 2004