Developmental validation of the DNATyper™Y26 PCR amplification kit: An enhanced Y-STR multiplex for familial searching.

The DNATyper™Y26 PCR Amplification kit, which including 26 low-medium mutating Y-STRs, is designed for Y-STR familial searching casework. The kit combines nine new Y-STR loci in addition to the 17 Y-STR loci from the commercially available AmpFlSTR®Yfiler® kit. The validation of the DNATyper™Y26 kit was performed in terms of technical index, including accuracy, stability, species specificity, sensitivity, adaptability for various samples, and mixture. Further, mutations of the 26 Y-STRs were analyzed by 1167 DNA-confirmed father-son pairs, and the results indicated that these loci had low or medium mutation rates. Furthermore, these Y-STRs loci were also tested in 1072 random male samples from Henan, Shanxi, Inner Mongolia, and Chongqing in China, showing their high power for forensic discrimination in the Chinese population. Thus, the DNATyper™Y26 PCR Amplification kit is a powerful tool for 'Y-STRs familial searching' in actual sexual-assault cases, indicating its unique advantage in familial searching due to Y-STR loci with only low-medium mutation rates.

New cell separation technique for the isolation and analysis of cells from biological mixtures in forensic caseworks.

AIM: To isolate mucosal cells of the perpetrator in a sexual assault case from a complex mixture of his mucosal cells and the victim's skin by micromanipulation prior to genomic analysis. METHODS: To capture and analyze mucosal cells we used the micromanipulation with on-chip low volume polymerase chain reaction (LV-PCR). Consensus DNA profiles were generated from 5 replicate experiments. RESULTS AND CONCLUSIONS: We validated the use of micromanipulation with on-chip LV-PCR for genomic analysis of complex biological mixtures in a fatal rape case. The perpetrator's mucosal cells were captured from nipple swabs of the victim, and a single-source DNA profile was generated from cell mixtures. These data suggest that micromanipulation with on-chip LV-PCR is an effective forensic tool for the analysis of specific cells from complex samples.

Individualization of tiger by using microsatellites.

In investigating criminal cases of poaching and smuggling involving tigers (Panthera tigris), the number of tiger individuals involved is critical for determining the penalty. Morphological methodologies do not often work because tiger parts do not possess the distinctive characteristics of the individual. Microsatellite DNAs have been proved a reliable marker for the individualization of animals. Seven microsatellite loci derived from domestic cat (Felis catus) were selected to individualize tigers, namely F41, F42, F146, Fca304, Fca391, Fca441 and Fca453. A reference population containing 37 unrelated tigers were used to investigate alleles, allelic frequencies, genotypes and genotype frequencies of each locus. Consequently, the data was used to assess the validity of the combination of seven loci for tiger individualization. All loci were polymorphic and easy to amplify. Three out of the seven loci were significantly departure from the Hardy-Weinberg Equilibrium (P < 0.05). Cumulative discrimination power (DP) calculated with observed genotype frequencies was 0.99999789. Match probability of an individual in the reference population with a random individual in seven loci ranged from 7.34 x 10(-9) to 2.77 x 10(-5). This suggests that combining the seven microsatellite loci provides desirable power to individualize tigers. The combination of seven loci was applied to a case of tiger bone smuggling. Genotypes of all samples were identical in all seven loci, and the P(M) of the evidence samples in the seven loci hit 5.63 x 10(-7), provided evidence that the bones belong to a single tiger.