Abstract
Y-STR genotyping is an excellent tool for the identification of DNA masked by female DNA, particularly in sexual assault cases where, more often the and female components cannot be separated completely. Resultant, the female component could exist prominently even in the component after separation. When the male DNA sample mixed with female DNA” undergoes PCR by using autosomal STR multiplex amplification process, the female DNA component is also amplified, mostly masking the DNA. Recently launched Y-STR kit, PowerPlex Y23 (PP Y23) System is a 5-dye multiplex genotyping kit that analyzes 17 Y-STR loci, commonly available in other Y-STR multiplex kits (DYS19, DYS385a/b, DYS389I/II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, DYS439, DYS448, DYS456, DYS458, DYS635, and Y-GATA-H4) along with that 6 new Y-STR loci (DYS481, DYS533, DYS549, DYS570, DYS576, and DYS643). The addition of 6 new markers has made the Y-STR analysis more discriminating. The purpose of the present study is to show the amplification of DNA from a wide variety of forensic samples using half the manufacturer’s recommended reaction volume. Also the present study validates the kit for its use in Forensic casework. The results demonstrate that the PPY23 System is a robust and sensitive multiplex system, capable of giving reliable and consistent amplification results from a wide variety of forensic casework samples. Even the presence of high concentration of commonly encountered inhibitors such as hematin (from Blood) and humic acid (from soil), male/female DNA mixtures and low amounts of DNA template (15.62 pg) could not hamper the process of amplification.
Highlights
Over the years forensic DNA typing has earned the credibility of forensic scientists
Increasing DNA quantity resulted in poor quality profiles with peaks imbalance; partial/total reaction inhibition was observed when working with too much DNA
All the samples tested with 200 pg DNA resulted in complete Y STR profile
Summary
Over the years forensic DNA typing has earned the credibility of forensic scientists. In routine forensic biological and serological examination of rape cases presence of semen and/or spermatozoa is detected, which cannot link the evidence to a particular suspect. Because of this fact DNA typing in sexual assault cases has proven to be a better solution. With the availability of genotyping markers for the NRY region, Y-DNA typing has become one of the most indispensable techniques in Forensic DNA typing, especially in sexual assault cases which bump into issues like unsuccessful separation of male and female cells. The forensic utility of Y-STRs is the result of their high levels of polymorphism in human populations [13], their small size in base pairs
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