混合斑的研究进展

The study on DNA mixtures

混合斑组成复杂,长期以来是法医物证研究的难题之一。混合斑主要分为两类:一是性侵害案件中大量女性阴道上皮细胞混合少量精子;二是普通来源的生物检材之间的混合,如血-血、唾液-血液混合等。近些年来,对混合斑的研究日渐深入,技术层面或理论分析都更加客观和多元化。针对第一类混合斑,出现了荧光/磁性激活、显微操纵、声波差异分离法等分离精子的新技术;第二类混合斑是研究的难点,近年来大规模平行测序、液滴微流控技术、乳液PCR(e PCR)、全基因组扩增等技术的出现,提高了次要成分的检出机率。此外,遗传标记也有相应的发展,传统遗传标记常染色体STR、Y-STR、SNP等检测位点越来越丰富,新兴遗传标记DIP、DIP-STR、SNPSTR、mt DNA-SNP、微单倍型等在混合斑研究中发挥的作用初步显露出来。文章最后涉及混合斑分析理论和计算软件的最新发展。

DNA mixture has been a problem to be conquered for a long time in the forensic study. The DNA mixtures can be mainly divided into two categories： one comes from the sex assaults, for which we have to detect the sperms among the large amount of vaginal epithelial cells; the other one is the combination of different common samples, such as blood mixtures, salvia-blood mixtures and so on. In recent years, deeper and deeper study on DNA mixtures has led a way to objectiveness and pluralism. Novel techniques, like fluorescence-or magnetic-activated cell sorting strategies,micromanipulation and acoustic different analysis can be utilized to separate sperms in the mixtures; as for the second sort, the application of massively parallel sequencing（MPS）, microfluidic droplet, wholegenome amplification, emulsion PCR（e PCR） et al. rise up the chances to detect the minor contributor in the mixtures. Furthermore, the development of both traditional and novel biomarkers which includes STR, Y-STR, SNP, DIP, Microhaplotype, DIP-STR, SNP-STR,, mt DNA-SNP and so on, provide us more analyzing choices in mixture study. The last part of the assay focuses on the latest progresses of evaluating the number of contributors, the explanation theory and calculation software.