Humans Are Animals,Too: Critical Commonalities and Differences Between Human and Wildlife Forensic Genetics

Wildlife forensics has recently been recognized among the wide variety of forensic science disciplines. This review compares human and wildlife DNA forensics, which use the same genetic tools, but often for far different purposes. Human forensic genetics almost invariably attempts to identify individual perpetrators involved in a given crime. Wildlife forensics often determines whether a crime has occurred. In addition to techniques familiar in human laboratories, like individual matching with STRs, wildlife analysts may be asked to determine the taxonomic identity, geographic source, or sex of evidence items, or the familial relationships or minimum number of individuals among a group of samples. This review highlights the common questions, legal framework, databases, and similar validation requirements to foster understanding between disciplines. Based on this understanding, human and wildlife DNA practitioners may work together and learn from each other in order to elevate the discipline of forensic genetics.     

Evaluation of genetic markers for the analysis of THC levels of Cannabis sativa samples using principal component analysis – A preliminary study

Cannabis sativa is a worldwide commercial plant used for medicinal purposes, food and fiber production, and also as a recreational drug. Therefore, the identification and differentiation between legal and illegal C. sativa is of great importance for forensic investigations. In this study, principal component analysis (PCA), an exploratory data analysis technique, was tested to correlate the specific genotype with the concentration of tetrahydrocannabinol (THC) in the samples. C. sativa samples were obtained from legal growers in Piedmont, Italy, and from illegal drug seizures in the Turin region. DNA was extracted, quantified, amplified with a 13-loci multiplex STR and finally analyzed with an automated sequencer. The results showed a trend in the analyzed samples as they differed by their THC content and allele profiles. PCA yielded two clusters of samples that differed by specific allele profiles and THC concentrations. Further validation studies are needed, but this study could provide a new approach to forensic investigation and be a valuable aid to law enforcement in significant marijuana seizures or in tracing illicit drug trafficking routes.     

Upon a failure to equal entry and exit wounds: a possible case of tandem bullets in view of the literature

Forensic medicine specialists take account of the projectiles remaining in the body when determining whether there are an equal number of entry and exit wounds. The absence of projectiles should suggest blank cartridges, a single exit wound despite several firings and bullet embolization, whereas the presence of more projectiles than expected may indicate tandem projectiles and multiple projectiles entering through the same hole. Radiological examination of the whole body, follow-up of the bullet trajectories, examination of the clothes, and examination of the gun and projectiles play a key role in solving difficult cases. We review such situations based on a case of tandem bullets. Two 7.65-mm bullets created lethal wounds entering through a 32-year-old victim's neck followed the same trajectory to a certain point and diverted. We discussed the possibilities in cases that show inequalities between entry and exit wounds, in light of relevant literature.     

判别函数在同胞鉴定中的应用

目的探讨判别函数法在全同胞与半同胞鉴定中的应用价值。方法根据360对全同胞、90对半同胞及360对无关个体的15个STR基因座分型结果,计算全不同(X0)、半相同(X1)和完全相同(X2)的基因座数目,分别根据DFS1=3.898X0+3.973X1-19.481,DHS1=5.687X0+5.300X1-35.112及DR1=7.309X0+5.533X1-44.941的全同胞/半同胞/无关个体判别函数、DFS2=3.872X0+3.931X1-18.895及DR2=7.303X0+5.473X1-44.298全同胞/无关个体判别函数和DHS3=10.227X0+10.436X1-66.102及DR3=11.863X0+11.089X1-79.494半同胞/无关个体判别函数进行判别。结果判别准确率:①用全同胞/半同胞/无关个体判别函数,全同胞组为83.61%,半同胞组为81.11%,无关个体组为83.06%;②用全同胞/无关个体判别函数,全同胞组为96.39%,无关个体组为98.61%;③用半同胞/无关个体判别函数,半同胞组为88.89%,无关个体组为85.00%。结论本文3种判别函数可应用于同胞鉴定,尤其运用全同胞/无关个体判别函数判断同胞关系准确率高,有较高的应用价值。     

五色荧光标记20个基因座复合扩增体系及法医学应用

目的建立20个基因座五色荧光标记复合扩增检测体系,并评价其法医学应用价值。方法收集368份无关人血样及55份实际案例样本(包括血斑、体液斑、组织及毛发),采用五色荧光素标记技术,对Amelogenin和19个STR基因座(D19S433、D5S818、D21S11、D18S51、D6S1043、D3S1358、D13S317、D7S820、D16S539、CSF1PO、Penta D、vWA、D8S1179、TPOX、Penta E、TH01、D12S391、D2S1338和FGA)进行基因型检测,并考察方法的一致性、灵敏度、种属特异性及检材适用性。结果本文五色荧光标记复合扩增检测体系可对所选20个基因座分型,结果稳定准确,且均衡性良好、无杂峰;群体调查显示累积个人识别率和累积非父排除率分别是0.999 999 999 999 999 999 999和0.999 999 99;灵敏度达125pg,种属特异性高,实际案例检材分型成功率高。结论本文五色荧光标记复合扩增检测体系各项指标可达到当前商品化试剂盒的检测水平,具有重要的法医学应用价值。     

国产Goldeneye~(TM) 20A试剂盒性能指标验证

目的测试国产GoldeneyeTM20A试剂盒技术性能指标,评估其法医学应用能力。方法从方法学验证、准确性、峰值均衡性、灵敏度、批次间试剂及稳定性测试、耐受性、不同检材的适应性与一致性、种属特异性、混合样本等9个方面对GoldeneyeTM20A试剂盒进行测试。结果阳性DNA样本分型正确,内标和等位基因分型标准物符合要求;等位基因间的均衡性≥83%,同一荧光标记基因座间的均衡性≥55%,不同标记物间的均衡性≥52%;0.125ng DNA阳性样本可检出全部STR基因座分型,不同批次间和反复冻融后试剂盒测试可以获得正确分型,对降解检材和混有抑制剂的样本等具有一定的耐受性,能对案件中多种检材进行分型且分型结果一致,具有一定的种属特异性和混合DNA样本检测能力。结论国产GoldeneyeTM 20A试剂盒可用于法庭科学实际检案与建库。     

Haplotypic blocks of X-linked STRs for forensic cases: study of recombination and mutation rates

In complex kinship cases, markers situated in haplotypic blocks may provide additional clues to other unlinked markers. We have established a protocol to amplify six X-chromosome microsatellites, located in two haplotype blocks, using PCR with fluorochrome-labeled primers and capillary electrophoresis. The segregation stability was explored in 92 unrelated families with individuals from three generations. Sixty-one different haplotypes were found in the DXS10079-DXS10074-DXS10075 block in the grandfathers and 96 in the mothers, with estimated haplotype diversities of 0.9828 and 0.9842, respectively. Fifty and 73 different haplotypes were found in the DXS6801-DXS6809-DXS6789 block in the grandfathers and the mothers, with estimated haplotype diversities of 0.9711 and 0.9742, respectively. We observed 10 between-cluster and one within-cluster recombinations in 99 female meioses. The overall per-locus mutation rate was 0.0034. This protocol allows for the characterization of the alleles of two sets of linked markers of the X-chromosome that can be useful in complex forensic cases.     

DNA identification of "Earthquake McGoon" 50 years postmortem

This report describes the genetic identification of James "Earthquake McGoon" McGovern, a WWII fighter ace who perished in Laos while providing supplies to French troops during the French Indochina war. Because reference samples were unavailable for all of the potential casualties, testing of the entire mitochondrial genome, autosomal STRs and Y-chromosomal STRs was performed to increase the genetic information available for analysis. Kinship analyses performed on the evidentiary data and numerous indirect family references for McGovern excluded other possible casualties and definitively established McGovern's identity. This particular case demonstrates the practical utility of novel research technologies and aggressive genetic typing protocols in the identification of aged, degraded remains.