This study details the differentiation of identical twins based on single mutational base differences. There were three pairs of male monozygotic (MZ) twins in this study. DNA samples from blood, a buccal swab or saliva from each individual were all initially genotyped using 22 autosomal STR and 27 Y-STR loci. Preliminary screening confirmed there were no differences in the STR data between each pair of MZ twins. Whole Genome Sequence (WGS) data were generated from DNA extracted from the three body fluids from each individual. Kinship coefficients with 0.4254, 0.4557 and 0.4543 from 3 twins were generated based on WGS data to further confirm that their relationship was that of MZ twins. The fastq data generated by the Illumina Hiseq 2000 between MZ twins were then treated as “normal” as opposed to “tumor” using commercially available software tools to identify mutational single base changes. Sanger DNA sequencing confirmed there were 1, 5 and 9 single base changes found in WGS data from each of the three MZ twin sets. There was individual variation in the mutational base changes when comparing data from the three body fluids. The methods used in this study to differentiate MZ twins based on WGS data can readily be performed in many operational forensic DNA laboratories using user friendly software.

这项研究详细介绍了基于单突变碱基差异的同卵双胞胎的分化。本研究中有三对男性同卵双胞胎。来自每个人的血液、口腔拭子或唾液的 DNA 样本最初均使用 22 个常染色体 STR 和 27 个 Y-STR 位点进行基因分型。初步筛查证实，每对同卵双胞胎之间的 STR 数据没有差异。全基因组序列 (WGS) 数据是从每个人的三种体液中提取的 DNA 生成的。根据WGS数据生成3对双胞胎的亲属关系系数分别为0.4254、0.4557和0.4543，进一步证实他们的关系是同卵双胞胎。然后，使用市售软件工具识别突变单碱基变化，将 Illumina Hiseq 2000 在同卵双胞胎之间生成的 fastq 数据视为“正常”而不是“肿瘤”。桑格 DNA 测序证实，三组同卵双胞胎的 WGS 数据中均发现了 1、5 和 9 个单碱基变化。当比较三种体液的数据时，突变碱基变化存在个体差异。本研究中使用的基于 WGS 数据区分同卵双胞胎的方法可以在许多正在运行的法医 DNA 实验室中使用用户友好的软件轻松执行。