DNA甲基化在法医DNA分析中的应用

表观遗传学在生命的发生、发展过程中起着十分重要的作用。DNA甲基化作为表观遗传的一个重要方面,不仅参与多种基因的表达调控,与机体的发育、肿瘤发生等密切相关,而且具有可遗传性、相对稳定性、亲缘特异性、基因组中含量丰富等特点,已证实适用于法医DNA分析。本文对近年来DNA甲基化在印迹基因、同卵双生子鉴定、年龄、性别推断方面的研究与应用进行回顾与综述,以期为在法医学及相关领域中应用提供参考。     

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.     

NONSHARED ENVIRONMENTAL INFLUENCES ON ADOLESCENT DELINQUENT INVOLVEMENT AND ADULT CRIMINAL BEHAVIOR*

Findings gleaned from behavioral genetic research have revealed that nonshared environments are particularly important sources of behavioral variation. Surprisingly little criminological research has examined directly the effects of the nonshared environment on adolescent delinquent involvement and adult criminal behavior. The current study addressed this gap in the literature by calculating difference scores in a sample of 289 monozygotic (MZ) twin pairs to examine the effects of the nonshared familial environment on delinquent involvement, adult criminal behavior, levels of self‐control, and contact with antisocial peers. Analysis of MZ twin pairs from the National Longitudinal Study of Adolescent Health (Add Health) revealed that one nonshared family environment—maternal disengagement—was associated with delinquent involvement and the development of self‐control. The remaining nonshared familial environments, however, were not associated with antisocial outcomes. Implications of the findings are discussed.     

microRNAs及其法医学应用前景

microRNAs(miRNAs)是一类内源性的非编码小分子RNA,平均长度约22nt,广泛存在于各种真核细胞中,并参与调节细胞生长发育、分化、凋亡、衰老、疾病及肿瘤的发生等众多重要生命活动。基于其生物学功能,miRNAs可能在法医学体液来源鉴定、个体年龄推断、同卵双生子甄别等方面具有广阔的应用前景。     

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]).     

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.     

拷贝数变异及其在法医学中的研究进展

近年来拷贝数变异的研究已逐渐延伸至各个领域,如复杂疾病病因探索、精准治疗以及遗传育种和进化等。拷贝数变异独有的遗传学特点使得人们逐渐相信其可以成为解决相关问题的生物学遗传标记。随着检测技术的发展,拷贝数变异在法医学方面的应用也将逐渐增多。本文就拷贝数变异概念与发展以及在法医学中的应用进行阐述,为今后拷贝数变异的实际应用提供新的思路。     

连体人的法律人格及其权利冲突协调

连体人属于民事主体中自然人的范畴。凡是具有独立人脑、具有独立的意志以及确定为一定的社会角色的连体人个体,都应当具有独立的法律人格。他们具有民事权利能力,但可能是无民事行为能力人、限制民事行为能力人或者欠缺民事行为能力人,因此需要以监护制度予以补正。他们的出生权、分离权在行使过程中会发生权利冲突,需要法律进行协调。