Exploring of rare differences in mtGenomes between MZ twins using massively parallel sequencing

Compared with nuclear DNA, fewer DNA repair mechanisms in mitochondria and lack of proofreading capabilities in the mtDNA polymerase help introduce more variability between MZ twins. In our previous study, we used ultra-deep mtGenome sequencing to characterize point heteroplasmy and nucleotide variant in blood samples of MZ twins. In the present study, we characterize minor differences of mtGenomes in saliva and hair shaft samples from six sets of MZ twins using the Precision ID mtDNA Whole Genome Panel, Ion S5 XL system, and Converge Software. Additionally, the effectiveness of different tissue samples for differentiating between MZ twins was evaluated. Point heteroplasmies were observed in all sets of MZ twins regardless of sample type. Overall, more variants were observed in the mtGenome from hair shaft samples than that from blood and saliva samples. The results of this study further support that the mtGenome analysis could be used to distinguish MZ twins from each other.     

同卵双生子外周血DNA甲基化谱的差异

目的通过比较不同个体外周血DNA甲基化谱的差异,评估DNA甲基化在同卵双生子个体甄别中的应用价值。方法在知情同意基础上获得22对同卵双生子外周血样。抽提基因组DNA后进行重亚硫酸盐转化．采用Illuraina公司的人27k甲基化微珠芯片检测基因组27578个CpG位点的甲基化程度（启值）。依据常染色体CpG位点的序值,采用欧氏距离计算方法计算同卵双生子间以及同性男ll的无关个体间的表观遗传距离。比较同卵双生子对与无关个体对两组不同人群间的表观遗传距离差异。结果同卵双生子对人群以及无关个体对人群中的男性个体对与女性个体对的表观遗传距离差异均无统计学意义（P值分别为0．0695和0．4825）。同卵双生子对的表观遗传距离显著低于无关个体对人群（中位数：6．02νs7．20,P=0．0002）．但两组人群的表观遗传距离均显著大于4．00（P〈0．0001）。结论同卵双生子间的外周血DNA甲基化谱差异显著．DNA甲基化是进行同卵双生子个体甄别的有效生物学标记。     

2例亲权鉴定案中的嵌合体STR谱分析

先天性基因嵌合体由遗传获得，是胚胎早期两个不同受精卵相互混合或血管交叉吻合继而发育成的一个包含两套（种）不同细胞系的个体。分为血型嵌合体（twin chimeras）和全身器官组织嵌合体（whole body chimerasl两种。本文通过两例亲权鉴定中发现的男性先天性嵌合体及其家族成员常染色体、性染色体的STR谱遗传分析，探讨先天性基因嵌合体的类型、发生、基因嵌合现象在不同组织中的表现及其作为证据可能在法庭科学调查中存在的风险。分析结果表明，两例男性Y—STR单倍型显示正常，分别与其男性家族成员Y—STR单倍型一致。但其在常染色体和X染色体上的STR基因表现嵌合现象，分别是在胚胎发育早期由男性-女性、男性-男性的异卵双生子发生融合并发育而成的的全身器官组织嵌合体。嵌合体上不同来源组织的STR等位基因强度显示不均衡状态。     

On the discriminability of the handwriting of twins

As handwriting is influenced by physiology, training, and other behavioral factors, a study of the handwriting of twins can shed light on the individuality of handwriting. This paper describes the methodology and results of such a study where handwriting samples of twins were compared by an automatic handwriting verification system. The results complement that of a previous study where a diverse population was used. The present study involves samples of 206 pairs of twins, where each sample consisted of a page of handwriting. The verification task was to determine whether two half-page documents (where the original samples were divided into upper and lower halves) were written by the same individual. For twins there were 1236 verification cases -- including 824 tests where the textual content of writing was different, and 412 tests where it was the same. An additional set of 1648 test cases were obtained from handwriting samples of nontwins (general population). To make the handwriting comparison, the system computed macro features (overall pictorial attributes), micro features (characteristics of individual letters), and style features (characteristics of whole-word shapes and letter pairs). Four testing scenarios were evaluated: twins and nontwins writing the same text and writing different texts. Results of the verification tests show that the handwriting of twins is less discriminable than that of nontwins: an overall error rate of 12.91% for twins and 3.7% for nontwins. Error rates with identical twins were higher than with fraternal twins. Error rates in all cases can be arbitrarily reduced by rejecting (not making a decision on) borderline cases. A level of confidence in the results obtained is given by the fact that system error rates are comparable to that of humans (lower than that of lay persons and higher than that of questioned document examiners [QDEs]).     

Differential Identification of Three Young Housefire Victims: Methods when Age Assessment Fails

Multiple fatality incidents involving more than one child of statistically same age (including twins) can be challenging from an identification standpoint. This case details an urban fire, in which four children perished. Age assessment on three of the victims utilizing maturity staging described by Moorrees, Fanning, and Hunt yielded insignificant results. However, a plot of the MFH data shows the difference between two identical twins and a third child. The twins share a similar growth pattern, whereas the other was different. Based on this graphical interpretation, the nontwin victim was positively identified through exclusion. These results were verified through statistical testing. This case demonstrates a method to repurpose age assessment data to graphically distinguish between child victims. Further, it is shown that radiographic and clinical presentation in childhood identical twins can elicit genetic versus acquired similarities and differences, which can be used for identification of individuals and exclusion of others.     

Comparison of fingernail striation patterns in identical twins.

The fingernail ridge patterns of a pair of identical twins were compared to each other, their parents, and an unrelated subject. The patterns of the twins' nails showed regions of strong similarity but were distinguishable from one another. Fewer similarities were found when comparing the nails to those of the parents and the unrelated control. The twins were shown to be monozygotic by means of DNA profiling. This therefore represents the first demonstration of unique fingernail ridge patterns in subjects shown conclusively to be identical twins. When the fingernail ridge patterns were examined with a scanning electron microscope, the backscattered electron (BEI) images were found to have superior contrast when compared to the secondary electron (SEI) images.     

SIBLING INTERACTION AND SELFREPORTED DELINQUENT BEHAVIOR: A STUDY OF 265 TWIN PAIRS*

The relationship between the quality of twins’mutual attachment and delinquency is examined in a study of 265 twin pairs. It is predicted that twins with stronger mutual attachments will have lower rates of delinquent behavior. Contrary to this prediction, twins’mutual attachment (that is, the frequency with which the twins saw each other in teenage activities) is found to be unrelated to delinquent behavior. The twins often cooperated, however, in their delinquent acts: 61 % of the girls and 79% of the boys reported committing one or more delinquent acts with their twins. In accord with social control theory, social bonds (normlessness, perceived parental acceptance-rejection, and value placed on academic achievement) are strongly associated with delinquent behavior. Except for male DZ twins, however, these same variables are only weakly associated with twins’mutual attachments. A behavioral genetic analysis of the social bonds indicate both genetic and specific environmental components to their variation but fail to show evidence of a shared environmental component. Implications of these findings are discussed.     

A test of the effectiveness of speaker verification for differentiating between identical twins

This paper presents investigations into the ability of speaker verification technology to discriminate between identical twins. It is shown that whilst, in general, the genetic and non-genetic characteristics of voice are both of value to speaker verification capabilities, it is the latter which is highly beneficial in the separation of the speech of identical twins. It is further demonstrated that through the use of unconstrained cohort normalisation as a complementary means for the exploitation of such voice characteristics, the verification reliability can be considerably enhanced for both identical twins and unrelated speakers. Experiments were conducted using a bespoke clean-speech database consisting of utterances from 49 identical twin pairs. The paper details the problem in speaker verification posed by identical twins, discusses the experimental investigations and provides an analysis of the results.     

The use of genomic "dactyloscopy" for the diagnosis of monozygotic twins

Possibilities of gene identification expertise for the solution of problem on mono- or dizygotic origin of twins were demonstrated. It was shown that DNA printing method makes it possible to differentiate mono- and dizygotic twins in complicated cases.     

同卵双生子甄别策略探讨

同卵双生子(MZ)之间存在抗体库差异、甲基化修饰差异和基因突变体差异,甲基化修饰差异的比较可望成为甄别MZ的手段之一,抗体库差异和基因突变体差异比较的方法在甄别MZ方面亦有潜在价值.当前,对MZ的表现遗传以及基因突变等领域的研究还很有限,而抗体库技术的应用方法也有待探讨,因此MZ识别技术的应用前景和发展空间需要进一步摸索与完善.     

1对同卵双生新生儿DNA甲基化谱差异分析

目的 探索1对同卵双生新生儿之间DNA甲基化谱的差异.方法 应用甲基化免疫共沉淀结合高通量测序法对1对同卵双生新生儿的DNA甲基化谱进行检测,分析基因组DNA甲基化特点及其之间的差异,筛选适用于法医学分析的甲基化位点.结果 两样本各获得7300万原始测序序列(raw reads)数据,与人类基因组参考序列比对,各得到4800万和5000万唯一比对reads,其中大部分分布在重复区域,且在Alu序列分布最为广泛.两样本DNA甲基化富集区域(peak)各检测到257 362条和197 272条,基因组覆盖率分别为6.53％和5.29％,分布在基因组不同区域,以中间内含子区含量最多.分析两样本甲基化差异区域得到2205条差异的甲基化序列,其中595条位于基因区域,1610条位于基因间区,从中筛选出113条序列,用于进一步深入研究其法医学应用价值.结论 本研究初步证实了DNA甲基化用于同卵双生子鉴定的可行性,为筛选同卵双生子DNA甲基化差异位点提供了基础数据.     

Simultaneous sudden infant death syndrome: a proposed definition and worldwide review of cases.

Epidemiologic studies of sudden infant death syndrome (SIDS), the leading cause of death of infants during the postperinatal period (7-365 days), have mainly focused on the deaths of single infants. Simultaneous sudden infant death syndrome (SSIDS), the death of a pair of twins occurring at the same time, has received limited attention within the medical community. To the authors' knowledge, this article is the first to describe the 41 SSIDS cases cited in the world literature from 1900 to 1998 by the location of death, a summary of the circumstances surrounding the deaths, and evaluation of these cases in terms of a proposed definition of SSIDS. This evaluation critiques whether the 41 pairs of SSIDS cases adhere to a newly proposed definition of SSIDS. Twin infant deaths must meet all three criteria to be considered SSIDS. The study found that only 12 pairs of twins met all three criteria (29.2%), nine pairs met two criteria (21.9%), alternative cause of death was offered in five pairs of twins (12.1%) and in the remaining 15 pairs (36.6%), only limited information was available; therefore, no conclusions could be reached.     

Microscopical discrimination of twins' head hair

Twin populations are ideal for studying human variation; a study of twin's hair, therefore, provided a better understanding of the value of hair comparisons. Duplicate head hair samples from 17 pairs of twins and one set of identical triplets were compared in a verified blind study. In addition to the direct comparison of all twins, random samples of two or three hairs were compared with randomly selected groups of known samples in a second blind study, to better simulate an ordinary forensic science case. Features commonly used by forensic hair examiners were adequate to distinguish hair samples from each twin from all other samples, illustrating the power of microscopical comparison when numerous questioned hairs are available in evidence. When two or three hairs were compared with randomly selected known samples, several were indistinguishable from hair samples other than the true source, proving once again that a human hair can never be associated with one person to the exclusion of all others.     

THE CONTAGIOUS NATURE OF ANTISOCIAL BEHAVIOR

Attention is called to several recently advanced lines of evidence underscoring the role of contagion in antisocial behavior. One line of evidence consists of findings that the onset of antisocial behavior in one sibling increases the risk to other siblings. A second line of evidence shows that the tendency of monozygotic twins to be more concordant for antisocial behavior than dizygotic twins can be explained by contagion as well as heredity. In addition, there are differences in prevalence between same-sexed and opposite-sexed twins that contagion can explain, but heredity cannot, at least not without numerous ad hoc auxiliary suppositions. Third, behavioral contagion is also able to explain, and very precisely, the temporal course of aggregate delinquency through adolescence. Fourth, evidence has been presented that antisocial behavior is an equilibrial phenomenon, that is, that it depends on a balance between antisocial and prosocial forces, a balance (or imbalance) that would explain the sudden leaps and falls that crime statistics sometimes take. Finally, programs to combat drug use are often modestly successful and almost all such programs presuppose that drug use is contagious. The paper closes with two sections on the implications of these findings, first for theory and research and then for policy and practice.     

In re A (children): in the Royal Courts of Justice (England)

HELD: The proposed operation to separate conjoined twins resulting in the death of one of the twins is lawful. Although Mary's death is foreseeable as an inevitable consequence of the operation, the invasive surgery is intended and necessary to save Jodie's life. Mary's death is not a purpose or intention of the surgery, and she will die only because her body, on its own, was never viable.     

不同频率共振峰在话者识别中的鉴别价值

目的研究在话者识别领域,不同频率共振峰特征价值的大小。方法对10对女性与8对男性双胞胎正常朗读语音的共振峰频率特性进行定量测量、比较、分析,统计。结果男性和女性双胞胎个体依据2000Hz以下、2000-5000Hz、5001-8000Hz不同频率范围内的共振峰均可区分,但共振峰的缺峰比例随着频率的升高而升高,5001-8000Hz范围的缺峰比例达26.67%。结论不同频率共振峰在话者识别中的区别能力无显著差异。     

从民法的角度看连体人的分离权

分离权是连体人特有的人格权,它是维护连体人个体独立存在的必然,是连体人个体充分享受自由的前提。连体人的分离权具有共有、依附、有限支配等法律属性,它的行使应遵循"不侵害生命原则"、"牺牲性分离须具正当性和合法性原则"、"子女最大利益原则"以及"法院最终决定原则"等。     

The genetic and environmental overlap between aggressive and non-aggressive antisocial behavior in children and adolescents using the self-report delinquency interview (SR-DI)

Purpose

This study investigated genetic and environmental commonalities and differences between aggressive and non-aggressive antisocial behavior (ASB) in male and female child and adolescent twins, based on a newly developed self-report questionnaire with good reliability and external validity -- the Self-Report Delinquency Interview (SR-DI).

Methods

Subjects were 780 pairs of twins assessed through laboratory interviews at three time points in a longitudinal study, during which the twins were: (1) ages 9-10 years; (2) age 11-13 years, and (3) age 16-18 years.

Results

Sex differences were repeatedly observed for mean levels of ASB. In addition, diverse change patterns of genetic and environmental emerged, as a function of sex and form of ASB, during the development from childhood to adolescence. Although there was some overlap in etiologies of aggressive and non-aggressive ASB, predominantly in shared environmental factors, their genetic overlap was moderate and the non-shared environmental overlap was low.

Conclusions

Taken together, these results reinforced the importance of differentiating forms of ASB and further investigating sex differences in future research. These results should be considered in future comparisons between youth self-report and parental or teacher report of child and adolescent behavior, and may help elucidate commonalities and differences among informants.     

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。     

Metal objects mapping after small charge explosions. A study on AISI 304Cu steel with two different grain sizes

Evidence of exposure of a metal component to a small charge explosion can be detected by observing microstructural modifications; they may be present even if the piece does not show noticeable overall plastic deformations. Particularly, if an austenitic stainless steel (or another metal having a face-centered cubic structure and a low stacking fault energy) is exposed to an explosive shock wave, high-speed deformation induces primarily mechanical twinning, whereas, in nonexplosive events, a lower velocity plastic deformation first induces slip. The occurrence of mechanical twins can be detected even if the surface is damaged or oxidized in successive events. In the present research, optical metallography (OM) and scanning electron microscopy (SEM), and scanning tunneling microscopy (STM) were used to detect microstructural modifications caused on AISI 304Cu steel disks by small-charge explosions. Spherical charges of 54.5 or 109 g TNT equivalent mass were used at explosive-to-target distances from 6.5 to 81.5 cm, achieving peak pressures from 160 to 0.5 MPa. Explosions induced limited or no macro-deformation. Two alloy grain sizes were tested. Surface OM and SEM evidenced partial surface melting, zones with recrystallization phenomena, and intense mechanical twinning, which was also detected by STM and X-ray diffraction. In the samples' interior, only twins were seen, up to some distance from the explosion impinged surface and again, at the shortest charge-to-sample distances, in a thin layer around the reflecting surface. For forensic science locating purposes after explosions, the maximum charge-to-target distance at which the phenomena disappear was singled out for each charge or grain size and related to the critical resolved shear stress for twinning.