Analysis of genetic polymorphisms associated with the presence of freckles for phenotypic prediction

The prediction of externally visible characteristics (EVCs) is a commonly used practice by the forensic sciences as an important resource in the investigation of criminal cases in which the identity of perpetrators or victims is unknown or even to recognize decomposed cadavers. With this purpose, genetic markers associated with pigmentation traits have been widely studied by forensic scientists and, nowadays, it is possible to predict phenotypic characteristics such as hair, eyes and skin colour, as well as the presence of skin freckles by analysing single nucleotide polymorphisms (SNPs). In this study, we analysed the association of six SNPs located in pigmentation genes to the presence of freckles in individuals from the Brazilian population for forensic DNA phenotyping. The study was based within the context of a larger project on a population sample of 534 adult Brazilians of both sexes and different skin colours. DNA was extracted from peripheral blood and genotyped using the TaqMan® OpenArray® Real-Time PCR System (ThermoFischer Scientific) technique. Statistical analyses were carried out with the R software (version 4.0.2). As for the results obtained, three SNPs were shown to be statistically associated to the freckling, rs12203592, rs1800404 and rs222847, with CT, AG and AA genotypes being the main contributors, respectively. Variables such as sex of the individuals and skin colour were found to also contribute to the manifestation of this pigmentation trait. Further statistical analyses will be carried out to evaluate the possibility of using the SNPs in this study for phenotyping prediction of the Brazilian population, improving existing DNA phenotyping models in forensic sciences.     

Human Leukocyte Antigen alleles as an aid to STR in complex forensic DNA samples

Human biological samples with multiple contributors remain one of the most challenging aspects of DNA typing within a forensic science context. With the increasing sensitivity of commercially available kits allowing detection of low template DNA, complex mixtures are now a standard component of forensic DNA evidence. Over the years, various methods and techniques have been developed to try to resolve the issue of mixed profiles. However, forensic DNA analysis has relied on the same markers to generate DNA profiles for the past 30 years causing considerable challenges in the deconvolution of complex mixed samples. The future of resolving complicated DNA mixtures may rely on utilising markers that have been previously applied to gene typing of non-forensic relevance. With Massively Parallel Sequencing (MPS), techniques becoming more popular and accessible even epigenetic markers have become a source of interest for forensic scientists.The aim of this review is to consider the potential of alleles from the Human Leukocyte Antigen (HLA) complex as effective forensic markers. While Massively Parallel Sequencing of HLA is routinely used in clinical laboratories in fields such as transplantation, pharmacology or population studies, there have not been any studies testing its suitability for forensic casework samples.     

Minisequencing-based genotyping of Duffy and ABO blood groups for forensic purposes

Duffy and ABO blood group genetic polymorphisms were studied by minisequencing analysis of single-nucleotide polymorphisms (SNPs) at nucleotide positions--33, 125, 265, and 298 of the Duffy gene and at nucleotide positions-261, 297, 467, 646, and 703 of the ABO gene. In an Italian population sample, we found four alleles and seven genotypes for the Duffy and six alleles and 16 genotypes for the ABO systems. The lower limit for reproducible results was 200 pg DNA, with a range of up to 10 ng and an optimum at 1 ng. All of the 16 analyzed inclusive paternity tests were also consistent with parentage and two out of four inconsistencies with parentage cases were excluded by one or more SNPs. Although Duffy and ABO SNP typing show lower informativeness than most current forensic tests, their robustness, the limited population distribution of FY* Fy type, and the sensitivity of the minisequencing technology suggest that these markers can be useful in selected forensic applications.     

The best possible result from the minimum available

In accordance with the Italian DNA legislation (DPR 7 April 2016, n. 87) a number of markers lower than seven are not considered usable for inclusion in the Italian forensic DNA database. For this reason, if the forensic DNA analysis performed in our laboratory do not provide acceptable results for a number greater than or equal to seven, the profile is not indicated in the final report. Thus, having indications about the possible success of an analysis before executing it, is a crucial point in the validation process of the accreditated method used in our laboratory.To achieve this goal, the quantification of extracts before typing plays a fundamental role. Especially when touched objects need to be examined tens or hundreds of nanograms may be present, but also very few or no cell can be present on the object. As such, quantification of every sample can ensure the maximum efficiency and prevent repeat analyses, over-amplified samples or completely useless examination.Quantifiler® Trio DNA quantification kit was validated in our laboratory according the guidelines approved by the ENFSI and always used before STR amplification of forensic casework DNA samples. Our attention has focused in particular on the definition of a minimum threshold at which it is useless to carry out DNA typing defining correlation of the negative results of the quantification by the absence of genetic profiles, as a result of DNA typing. Moreover, the validation of the Savant™ SPD131DDA SpeedVac™ Concentrator to get the maximum possible yield from DNA extracts was also investigated.     

Reliability of the methods applied to assess age minority in living subjects around 18 years old. A survey on a Moroccan origin population

We present a review of a population of 114 immigrant Moroccan males for which an age estimation was requested. The subjects' real chronological age was confirmed by the Moroccan Embassy in Spain. The confirmed age range was between 13 and 25, with an average age of 18.1 years and a standard deviation of 2.03. The following tests were performed to arrive at the forensic estimation of age: general physical examination, carpus X-ray (Greulich and Pyle method) and dental orthopantomography to determine the degree of maturity of the third inferior molars (Demirjian's method). Carpus X-ray (skeletal age) was the most useful method, followed by Demirjian's method (dental age), as prediction factors of a chronological age of over or under 18. The combination of skeletal and dental age variables represented a significant improvement in the prediction of the chronological age of the subjects in this population, reducing the number of ethically unacceptable test errors to a minimum.     

DNA芯片分析单核苷酸多态性及其法医学应用

DNA芯片技术作为一门新兴的高科技生物技术,显示了它旺盛的生命力和迅猛的发展势头。单核苷酸多态性(SingleNucleotidePolymorphisms,SNPs)是最常见的人类基因组变异类型。它作为一种有效的人类遗传标记,在疾病相关性研究、药物基因组学、法医学、人类进化和迁移等研究中发挥了重要作用。它同DNA芯片技术结合运用也将在法医检验,尤其是亲子鉴定和个人识别中发挥重要作用。本文主要讨论了DNA芯片和SNPs的特点,以及二者联合运用于法医学的价值。     

Allele sequences of six new Y-STR loci and haplotypes in the Chinese Han population

Human chromosome Y-specific short tandem repeat (Y-specific STR) markers have useful properties for forensic applications. However, there is a need to develop more Y-specific STR markers, because the discriminating power of each STR locus is limited. In the present study, we describe our results on six new Y-specific STR markers that were initially located using sequence database information by Ayub et al. and were named DYS434, DYS435, DYS436, DYS437, DYS438 and DYS439. Our studies focused on the analysis of the DNA sequence for each allele at all six Y-specific STR loci in order to understand their structures in the human genome and to construct human allelic ladders, which are necessary for forensic DNA typing. In addition, the haplotype distribution for all six analyzed loci was studied in a Chinese Han population sample. The results indicate that DYS434, DYS435, DYS436, DYS437, DYS438 and DYS439 are useful Y-specific STR markers for forensic sciences.     

Studies of the chronological course of wisdom tooth eruption in a Japanese population

The importance of forensic age estimation in living subjects has grown over the last few years. In dental age estimation, tooth eruption is a parameter of developmental morphology that can be analyzed by either clinical examination or by evaluation of dental X-rays. In the present study, we determined the stage of wisdom tooth eruption in 549 male and 751 female Japanese subjects aged 14-26 years based on radiological evidence from 1300 conventional orthopantomograms. The results presented here provide useful data on the age of alveolar, gingival, and complete emergence of the third molars in the occlusal plane that can be utilized for forensic estimation of the minimum and most probable ages of investigated persons.     

STR analysis of degraded DNA using a miniplex

Analysis of short tandem repeat (STR) markers currently represents the most useful instrument in the field of forensic genetics. The problem with forensic material is the degradation of the sample material. In recent years, several papers have demonstrated that short amplicon STR (miniSTR) represents one of the most useful tools for analyzing degraded DNA samples.In the present study, we attempted to develop a short amplicon STR multiplex system (autosomal and y-chromosomal) for analyzing degraded DNA using some newly designed primer sets for a multiplex polymerase chain reaction (PCR) systems for typing.An assay of degraded DNA samples using the designed multiplex systems, including artificially degraded samples and degraded forensic casework samples, proved remarkably effective. Comparing the multiplex with commercial kits, first results show a well success rate.     

A novel multiplex assay system based on 10 methylation markers for forensic identification of body fluids

Identifying the source of body fluids found at a crime scene is an essential forensic step. Some methods based on DNA methylation played significant role in body fluids identification. Since DNA methylation is related to multiple factors, such as race, age, and diseases, it is necessary to know the methylation profile of a given population. In this study, we tested 19 body fluid-specific methylation markers in a Chinese Han population. A novel multiplex assay system based on the selected markers with smaller variation in methylation and stronger tissue-specific methylation were developed for the identification of body fluids. The multiplex assay were tested in 265 body fluid samples. A random forest model was established to predict the tissue source based on the methylation data of the 10 markers. The multiplex assay was evaluated by testing the sensitivity, the mixtures, and old samples. For the result, the novel multiplex assay based on 10 selected methylation markers presented good methylation profiles in all tested samples. The random forest model worked extremely well in predicting the source of body fluids, with an accuracy of 100% and 97.5% in training data and test data, respectively. The multiplex assay could accurately predict the tissue source from 0.5 ng genomic DNA, six-months-old samples and distinguish the minor component from a mixture of two components. Our results indicated that the methylation multiplex assay and the random forest model could provide a convenient tool for forensic practitioners in body fluid identification.     

Three-dimensional modeling of the various volumes of canines to determine age and sex: a preliminary study

Canines are usually used in anthropological and forensic sciences for sex and age determination. The best methods to estimate age are based on secondary dentine apposition, evaluated from periapical X-rays. The aim of this study was to propose a new method of sex and age estimation using 3D models to obtain more precise predictions using tooth volumes. Fifty-eight dental CT scans of patients aged 14-74 with a well-balanced sex ratio composed the sample. One hundred and thirty-three healthy canines were modeled (Mimics 12.0). The sample was divided into a training sample and a validation sample. An age formula was determined using the "pulp volume/tooth volume" ratio. Sex prediction was adjusted with total volumes. Applying the equations to the validation sample, no significant difference was found between the real and predicted ages, and 100% of the sex predictions were correct. This preliminary study gives interesting results, and this method is worth being tested on a larger data sample.     

Empirical testing of estimated DNA frequencies

Direct empirical testing of forensic DNA micro-probabilities has proved difficult. Substantial support for the population genetic models on which these micro-probabilities are based has come from powerful but indirect means. However for many people empirical testing rather than models remains the ideal.Following the example set by Weir and Evett we report here a large-scale empirical test of a population genetic model incorporating substructure and relatedness. Given that all models represent simplifications of reality the fit of observed and prediction is remarkable and gives substantial support to the reliability of current methods.     

Studies of the chronological course of wisdom tooth eruption in a Black African population

The importance of forensic age estimation in living subjects has grown over the last few years. In dental age estimation, tooth eruption is a parameter of developmental morphology that can be analyzed by either clinical examination or by evaluation of dental X-rays. In the present study, we determined the stage of wisdom tooth eruption in 410 male and 106 female Black South African subjects of known age (12-26 years) based on radiological evidence from 516 conventional orthopantomograms. Four eruption stages were determined (no emergence, alveolar emergence, gingival emergence, complete emergence). Statistical scores were determined for the individual stages separately for both sexes. The data presented here can be utilized for forensic estimation of the minimum and most probable ages of investigated persons.     

Forensic Analysis of mtDNA Haplotypes from Two Rural Communities in Haiti Reflects Their Population History

Abstract: Very little genetic data exist on Haitians, an estimated 1.2 million of whom, not including illegal immigrants, reside in the United States. The absence of genetic data on a population of this size reduces the discriminatory power of criminal and missing‐person DNA databases in the United States and Caribbean. We present a forensic population study that provides the first genetic data set for Haiti. This study uses hypervariable segment one (HVS‐1) mitochondrial DNA (mtDNA) nucleotide sequences from 291 subjects primarily from rural areas of northern and southern Haiti, where admixture would be minimal. Our results showed that the African maternal genetic component of Haitians had slightly higher West‐Central African admixture than African‐Americans and Dominicans, but considerably less than Afro‐Brazilians. These results lay the foundation for further forensic genetics studies in the Haitian population and serve as a model for forensic mtDNA identification of individuals in other isolated or rural communities.     

镫骨肌声反射推算听敏度及法医学评价

听力损害的法医学鉴定，须采用客观、准确、定量的听力测验方法。声镫骨肌反射具有客观、设备简单、操作方便快捷、检查费用低廉等优点。国外学者对此进行了较多研究，结果差异较大。国内这方面研究较少。本文按严格纳入标准，选择大样本运用逐步多元回归统计分析，建立了推算ＰＴＡ的数学模型，经统计学显著性检验，新建方程具有较高准确性。且可信度均较过去推算方法为好。年龄、中耳阻抗轻度异常对推算准确性无显著影响。声镫骨肌推算听敏度数学模型仍可作为法医学鉴定中客观评定听力下降程度的首选常规方法。     

General and maladaptive traits and anger in a combined forensic psychiatric and general population sample

The present study examines the associations between anger and general and maladaptive traits in a combined forensic psychiatric and community sample of men. Thirty-four male forensic psychiatric patients and 219 men from the general population completed the Novaco Anger Scale (NAS; Novaco, 1994), the NEO-PI-R (Costa & McCrae, 1992), the ADP-IV (Schotte & De Doncker, 1994) and the VKP (Duijsens, Haringsma, & EurelingsBontekoe, 1999) at two measurement occasions with a one-year interval. The results of a series of multiple regression analyses showed that general and maladaptive traits accounted for a substantial amount of variance in anger scores. Neuroticism, Agreeableness and Externalizing traits were most prominent in the prediction of anger, while Conscientiousness was acting as a suppressor variable in the regression models. Strengths and limitations of the present study and implications for further research and clinical practice are discussed.     

DNA甲基化在法医学中的应用前景及其检测方法新进展

DNA甲基化是一种重要的表观遗传标记。新近的一些研究表明,DNA甲基化在二联体亲权鉴定、同卵双生子法医学个体甄别等案例中可能具有一定的应用前景,可作为STR或SNP等经典遗传标记的有益补充。目前基于甲基化敏感的限制性核酸内切酶、重亚硫酸盐转化以及甲基化CpG结合蛋白等原理已建立了一系列的DNA甲基化检测方法。甲基化敏感的单核苷酸引物延伸、实时荧光PCR、甲基化特异性PCR、甲基化特异性多重连接反应依赖性探针扩增、光纤微珠芯片等位点特异性DNA甲基化检测方法都可用于已知CpG位点甲基化状态的检测并可能在法医学实验室具有一定的应用前景;AIMS、HELP、COMPARE-MS等通过对基因组范围内的DNA甲基化扫描分析,可发现具有潜在法医学应用价值的DNA甲基化位点。     

Methylation-Based Age Prediction Using Pyrosequencing Platform from Seminal Stains in Han Chinese Males

Various methods have been performed to predict an unknown individual's age from biological traces in forensic investigations. A considerably accurate age prediction for the semen donor can help narrow down the search in a sexual assault case. The aim of this study was to develop an assay for age prediction from seminal stains in Han Chinese males. We built a sperm-specific linear regression model using bisulfite pyrosequencing. Validations were conducted with a Mean Absolute Deviation from the chronological age (MAD) of 4.219 years in liquid semen, 4.158 years in fresh seminal stains, 4.393 years in aged seminal stains, and 3.880 years in mixed stains, respectively. Furthermore, our strategy enables accurate age prediction using a forensic casework sample. The strategy indicated that we produced an accurate and reliable age prediction tool for the semen donors in Han Chinese males for forensic purposes.     

A New Approach of Juvenile Age Estimation using Measurements of the Ilium and Multivariate Adaptive Regression Splines (MARS) Models for Better Age Prediction

Juvenile age estimation methods used in forensic anthropology generally lack methodological consistency and/or statistical validity. Considering this, a standard approach using nonparametric Multivariate Adaptive Regression Splines (MARS) models were tested to predict age from iliac biometric variables of male and female juveniles from Marseilles, France, aged 0–12 years. Models using unidimensional (length and width) and bidimensional iliac data (module and surface) were constructed on a training sample of 176 individuals and validated on an independent test sample of 68 individuals. Results show that MARS prediction models using iliac width, module and area give overall better and statistically valid age estimates. These models integrate punctual nonlinearities of the relationship between age and osteometric variables. By constructing valid prediction intervals whose size increases with age, MARS models take into account the normal increase of individual variability. MARS models can qualify as a practical and standardized approach for juvenile age estimation.     

Genetic profiling of a central Venezuelan population using 15 STR markers that may be of forensic importance

The AmpFlSTR Identifiler kit has recently been accepted for use in DNA databasing of forensic samples in the FBI's National DNA Index System. In the present study, we used this kit to analyze the allele distribution of 15 short tandem repeat markers (STR) in individuals living in Caracas city, Venezuela. The allele frequencies of two of these STR, D2S1338 and D19S433, have not previously been reported for this or any other Latin American population. The results indicate that for the population here studied, the 15 STR tested are useful markers for paternity testing and forensic casework.