A developmental validation study was performed on three Y-STR DNA multiplex systems--Multiplex III (MPIII), Multiplex IV (MPIV), and Multiplex V (MPV)--in order to determine their potential application to forensic casework.
Full genetic profiles were consistently obtained for all three multiplexes with 25-50 pg of male DNA. No significant amplification was observed with 1 mg of female DNA. Each multiplex permitted the determination of the number of male donors in male:male DNA admixtures. Species specificity studies demonstrated some cross-reactivity with some primate samples. Environmentally compromised blood samples produced full or partial profiles after exposure to various conditions for up to 1 year. Full profiles were recovered from simulated casework specimens, including cigarette butts and postcoital cervicovaginal swabs. Population data were collected to determine individual loci gene diversity and multiplex discriminatory capacity. Rigorous performance checks on the optimized systems and an evaluation of the systems' abilities to discriminate between unrelated males demonstrated their potential utility in forensic casework. The three Y chromosome STR multiplex systems that allow for the co-amplification of 8 (+YAP) (MPIII), 21 (MPIV), and 13 (MPV) "noncore" Y-STRs, respectively, underwent a full developmental validation according to revised guidelines proposed by the Scientific Working Group on DNA Analysis Methods. One of the reasons why it may be necessary to use additional Y chromosome markers beyond the core set is to provide additional discriminatory power in an attempt to distinguish between two male suspects who share the same core loci haplotype. A second reason is to provide stronger statistical support for the evidence sample and the known sample (or a biological male relative) having a common origin. The authors envision that studies such as those described in this paper will provide suitable candidate loci for possible inclusion into second-generation noncore loci commercial kits. 8 figures, 5 tables, and 49 references