Department of Mathematical Sciences, Aalborg University, Fredrik Bajers Vej 7G, DK-9220 Aalborg East, Denmark.
Forensic Sci Int Genet. 2012 Jan;6(1):97-101. doi: 10.1016/j.fsigen.2011.03.001. Epub 2011 Apr 1.
DNA samples found at a scene of crime or obtained from the debris of a mass disaster accident are often subject to degradation. When using the STR DNA technology, the DNA profile is observed via a so-called electropherogram (EPG), where the alleles are identified as signal peaks above a certain level or above a signal to noise threshold. Degradation implies that these peak intensities decrease in strength for longer short tandem repeat (STR) sequences. Consequently, long STR loci may fail to produce peak heights above the limit of detection resulting in allelic or locus drop-outs. In this paper, we present a method for measuring the degree of degradation of a sample and demonstrate how to incorporate this in estimating the probability of allelic drop-out. This is done by extending an existing method derived for non-degraded samples. The performance of the methodology is evaluated using data from degraded DNA, where cases with varying amounts of DNA and levels of degradation are investigated.
在犯罪现场发现或从大规模灾难事故的残骸中获取的 DNA 样本通常会受到降解。在使用 STR DNA 技术时，通过所谓的电泳图 (EPG) 观察 DNA 图谱，其中等位基因被识别为高于一定水平或高于信号噪声阈值的信号峰。降解意味着这些峰强度对于较长的短串联重复 (STR) 序列的强度降低。因此，长 STR 基因座可能无法产生高于检测限的峰高，从而导致等位基因或基因座缺失。在本文中，我们提出了一种测量样本降解程度的方法，并展示了如何将其纳入估计等位基因缺失概率的方法中。这是通过扩展为非降解样本推导的现有方法来完成的。通过使用来自降解 DNA 的数据评估该方法的性能，其中研究了具有不同 DNA 量和降解水平的情况。
