ABSTRACT
Objective To investigate the significance of a comprehensive test on the semen stain in the field of forensic evidence;Methods PSA tests performed on samples obtained supernatant and sediment STR genotyping by differential lysis method;Results Through STR testing,there are inconsistencies with the PSA test results in which 13 cases of false positive and false negative in 1 case.The supernatant was detected in two cases of male component,coeducational 9 cases;Conclusion PSA test strips there are some false positive and false negative rate,test isolated by the difference lysis supernatant can not only increase the success rate of the fine on the semen stain can also as a supplement to bring more valuable information for the semen stain.
ABSTRACT
Objective To study primary transfer and secondary transfer of exfoliated cells by handshaking and touching. Methods Firstly, volunteers wash hands , then shake hands between two volunteers, after that each volunteer touch the cleaned glass. Finally, pick up the DNA from the glass. Results STR loci that can be extracted from glasses. Under the same conditions, the number of STR loci obtained by primary transfer is more than that obtained by the secondary transfer. Conclusion Primary transfer and secondary transfer of exfoliated cells could happened by handshaking and touching. Therefore, in forensic work, we should pay great attention to the pollution problems caused by DNA transfer.
ABSTRACT
To ensure the consistency of genotype results for PowerPlex?21 kit and GoldeneyeTM 20A kit. Methods The STR loci were amplified in DNA samples from 205 unrelated individuals in Beijing Han population. And consistency of 19 overlap STR loci typing were observed. The genetic polymorphism of D1S1656 locus was obtained. Results All 19 overlap loci typing showed consistent. The proportion of peak height of heterozygous loci in two kits showed no statistical difference (P>0.05). The observed heterozygosis of D1S1656 was 0.878. The discrimination power was 0.949. The excluding probability of paternity of triplet was 0.751. The excluding probability of paternity of diploid was 0.506. The polymor-phism information content was 0.810. Conclusion PowerPlex?21 kit and GoldeneyeTM 20A kit present a good consistency. The primer design is reasonable. The polymorphism of D1S1656 is good. The two kits can be used for human genetic analysis, paternity test, and individual identification in forensic practice.