Y-STRs in forensic medicine: DNA analysis in semen samples of azoospermic individuals

ABSTRACT: The incidence of rape has increased, especially in metropolitan areas, such as the city of São Paulo. In Brazil, studies about it have shown that the majority of this type of crime is committed by the relatives and persons close to the victim. This has made the crime more difficult to be denounced, as only 10% of the cases are reported to competent police authorities. Usually, cytological exams are carried out in sex crime investigations. The difficulty in showing the presence of spermatozoa is frequent, but it does not exclude the presence of male DNA. The absence of spermatozoa in material collected from rape victims can be due to several factors, including the fact that the agressor suffers from azoospermia. This condition can be the result of a successful vasectomy. As the majority of DNA in the ejaculation sample is from spermatozoa, there is much less DNA to be analyzed. This study presents the application of Y‐STRs (DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, and DYS393) in DNA analysis of sperm samples from 105 vasectomized men. The study demonstrated a great variation in DNA concentration. DNA extraction and amplification was possible in all sperm samples even in the absence of spermatozoa. The same profile was observed, for each individual, from DNA extracted from blood, pre‐ and postvasectomy semen samples. The use of markers specific for Y chromosome in sex crime cases, especially in the absence of spermatozoa, is very important, mainly because in most situations there is a small quantity of the agressor's DNA in the medium and a large quantity of the victim's DNA.     

Population substructure can significantly affect reliability of a DNA-led process of identification of mass fatality victims

Aiming to evaluate the effects of population substructure on the reliability of a DNA correspondence in the process of human identification, we used the model of "in silico" constructed populations with and without substructure. Effects of population substructure were evaluated at the level of locus heterozygosity, Hardy-Weinberg equilibrium and mini-haplotype distribution. Inbreeding in a subpopulation of 100 individuals through 10 generations did not significantly alter the level of heterozygosity and Hardy-Weinberg equilibrium. However, analysis of mini-haplotype distribution revealed a significant homogenization in separated subpopulations. Average observed mini-haplotype frequency (f(o)) increased to threefold from expected values (f(e)), and the number of mini-haplotypes with f(o)/f(e) above 10 increased over sixfold, suggesting that the effects of population substructure on calculated likelihood ratios (LR) might be larger than previously estimated. In most criminal cases, this would not represent a problem, whereas for identifications in large-scale mass fatality events, population substructure might considerably increase the risk of false identification.     

Recovery of Environmental Human DNA by Insects*,†

Abstract: We tested the hypotheses that foraging insects can acquire human DNA from the environment and that insect‐delivered human DNA is of sufficient quantity and quality to permit standard forensic analyses. Houseflies, German cockroaches, and camel crickets were exposed to dusty surfaces and then assayed for human mitochondrial and nuclear loci by conventional and qPCR, and multiplex STR amplification. Over two experiments, 100% of insect groups and 94% of dust controls tested positive for human DNA. Of 177 individuals, 33–67% tested positive and 13 yielded quantifiable human DNA (mean = 0.022 ± 0.006 ng; mean dust control = 2.448 ± 0.960 ng); four had at least one positive allele call for one or more locus; eight others showed multiple peaks at some loci. Results imply that application to routine forensic casework is limited given current detection methodology yet demonstrate the potential use of insects as environmental samplers for human DNA.     

Trace DNA Sampling Success from Evidence Items Commonly Encountered in Forensic Casework

Trace DNA analysis is a significant part of a forensic laboratory's workload. Knowing optimal sampling strategies and item success rates for particular item types can assist in evidence selection and examination processes and shorten turnaround times. In this study, forensic short tandem repeat (STR) casework results were reviewed to determine how often STR profiles suitable for comparison were obtained from “handler” and “wearer” areas of 764 items commonly submitted for examination. One hundred and fifty‐five (155) items obtained from volunteers were also sampled. Items were analyzed for best sampling location and strategy. For casework items, headwear and gloves provided the highest success rates. Experimentally, eyeglasses and earphones, T‐shirts, fabric gloves and watches provided the highest success rates. Eyeglasses and latex gloves provided optimal results if the entire surfaces were swabbed. In general, at least 10%, and up to 88% of all trace DNA analyses resulted in suitable STR profiles for comparison.     

Evaluation of a Freezer Mill for Bone Pulverization prior to DNA Extraction: An Improved Workflow for STR Analysis

Traditional methods for bone pulverization typically generate heat, risking stability of DNA sample. SPEX? has developed cryogenic grinders which introduce liquid nitrogen to cool the sample and aid in the grinding process. In this study, the Freezer Mill 6970 EFM was used with two DNA extraction methods and routine downstream STR analysis procedures. DNA from as little as 0.1 g of bone powder was used to develop full STR profiles after freezer mill pulverization, and the method was reproducible. Further, no contamination was detected upon cleaning/reuse of the sample vials. There were no significant differences in DNA yield, STR alleles detected, or peak heights using the freezer mill as compared to traditional grinding, and successful DNA profiles were achieved from as low as 0.1 g of bone powder with this method. Overall, this work indicates that this cryogenic mill method may be used as a viable alternative to traditional tissue grinders.     

基于二代测序的混合检材精细化分型研究

目的基于二代测序平台进行混合检材精细化STR分型,并评估其法医学应用价值。方法收集性侵案件中3例混合检材及其比对样本,采用M48磁珠提取纯化试剂盒提取样本DNA,使用Foren SeqTM DNA Signature Prep试剂盒制备文库,Mi Seq FGx平台进行测序,Foren SeqTM Universal Analysis v1.2.1软件进行数据分析,将STR序列多态分型与长度多态分型进行比较。结果对3例混合检材STR分型进行拆分,在D3S1358、D13S317与D9S1122基因座发现存在同一长度多态等位基因包含两个个体的序列多态等位基因的情况。结论二代测序技术可对混合检材进行精细鉴别,为混合分型数据拆分提供更多线索和依据。     

Focused Deterrence Strategies and Crime Control

Research Summary

Focused deterrence strategies are increasingly being applied to prevent and control gang and group‐involved violence, overt drug markets, and individual repeat offenders. Our updated examination of the effects of focused deterrence strategies on crime followed the systematic review protocols and conventions of the Campbell Collaboration. Twenty‐four quasi‐experimental evaluations were identified in this systematic review. The results of our meta‐analysis demonstrate that focused deterrence strategies are associated with an overall statistically significant, moderate crime reduction effect. Nevertheless, program effect sizes varied by program type and were smaller for evaluations with more rigorous research designs.

Policy Implications

The available empirical evidence suggests these strategies generate noteworthy crime reduction impacts and should be part of a broader portfolio of crime reduction strategies available to policy makers and practitioners. Investments still need to be made, however, to strengthen the overall rigor of program evaluations and improve our understanding of key program activities associated with observed crime reduction impacts.     

山东汉族人群19个STR基因座的遗传多态性

目的调查山东汉族人群19个STR基因座的群体遗传学资料,为亲权鉴定提供遗传学数据。方法采用GoldeneyeTM20A试剂盒对山东汉族人群中205例无关个体进行基因分型,得到19个STR基因座的等位基因频率及群体遗传学参数。对Identifile一、SinoFilerTM、PowerPlex16和GoldeneyeTM20A4个试剂盒进行比较,并对l例特殊的亲子鉴定案件进行分析。结果获得山东汉族人群19个STR基因座的群体遗传学参数。累积个体识别率（CDP）及累积非父排除率（CPE）从高到低分别为GoldeneyeTM20A、SinoFilerTM、PowerPlex16、IdentifilerTM试剂盒。对实际案件进行分析．作为二联体,IdentifilerTM试剂盒无被排除基因座,而SinoFilerTM、PowerPlex16和GoldeneyeTM20A试剂盒均不能排除父子关系。结论与IdentifilerTM、SinoFilerYn和PowerPlex163种试剂盒进行比较．GoldeneyeTM20A试剂盒效能更高．但不能完全满足二联体鉴定的要求。     

Genetic Polymorphisms of 15 STR Loci in Gansu Hui Population

The short tandem repeat （STR） markers are widely used in human identification and paternity testing in the field of forensic geneticsm. Recent re- searches on polymorphic STRs have led to their applications to population genetics, forensic DNA database, human individual identification, paternity testing, genetic mapping, disease linkage analysis, archaeology and potential inference of the ethnic o- rigin of an individual.     

Repeat Citizens in Motor Vehicle Stops

ABSTRACT

This paper explores the possible existence of the repeat phenomenon and their impact on racial disparities in police motor vehicle stops. The repeat phenomenon is the existence of a small proportion of people or places that account for a much larger proportion of events. While this phenomenon has been identified and discussed in other areas of criminal justice and criminology, it has not been extended to motor vehicle stops. The current study examines the existence of repeat citizens in a population of motor vehicle stops (N = 4775) from a Mid-western city during 2001. A small, but significant, concentration of motor vehicle stops were discovered among a few citizens and significant predictors of citizen performance included citizen race, gender, age, residency, time of the stop, and reason for the stop.