Alghanim Hussain, Antunes Joana, Silva Deborah Soares Bispo Santos, Alho Clarice Sampaio, Balamurugan Kuppareddi, McCord Bruce
Department of Chemistry and Biochemistry, Florida International University, Miami, FL, USA; General Department of Forensic Science and Criminology, Dubai Police, Dubai, United Arab Emirates.
Department of Chemistry and Biochemistry, Florida International University, Miami, FL, USA.
Forensic Sci Int Genet. 2017 Nov;31:81-88. doi: 10.1016/j.fsigen.2017.07.011. Epub 2017 Aug 7.
Recent developments in the analysis of epigenetic DNA methylation patterns have demonstrated that certain genetic loci show a linear correlation with chronological age. It is the goal of this study to identify a new set of epigenetic methylation markers for the forensic estimation of human age. A total number of 27 CpG sites at three genetic loci, SCGN, DLX5 and KLF14, were examined to evaluate the correlation of their methylation status with age. These sites were evaluated using 72 blood samples and 91 saliva samples collected from volunteers with ages ranging from 5 to 73 years. DNA was bisulfite modified followed by PCR amplification and pyrosequencing to determine the level of DNA methylation at each CpG site. In this study, certain CpG sites in SCGN and KLF14 loci showed methylation levels that were correlated with chronological age, however, the tested CpG sites in DLX5 did not show a correlation with age. Using a 52-saliva sample training set, two age-predictor models were developed by means of a multivariate linear regression analysis for age prediction. The two models performed similarly with a single-locus model explaining 85% of the age variance at a mean absolute deviation of 5.8 years and a dual-locus model explaining 84% of the age variance with a mean absolute deviation of 6.2 years. In the validation set, the mean absolute deviation was measured to be 8.0 years and 7.1 years for the single- and dual-locus model, respectively. Another age predictor model was also developed using a 40-blood sample training set that accounted for 71% of the age variance. This model gave a mean absolute deviation of 6.6 years for the training set and 10.3years for the validation set. The results indicate that specific CpGs in SCGN and KLF14 can be used as potential epigenetic markers to estimate age using saliva and blood specimens. These epigenetic markers could provide important information in cases where the determination of a suspect's age is critical in developing investigative leads.
表观遗传DNA甲基化模式分析的最新进展表明，某些基因位点与实际年龄呈线性相关。本研究的目的是确定一组新的表观遗传甲基化标记物，用于法医鉴定人类年龄。研究人员检测了三个基因位点（SCGN、DLX5和KLF14）上总共27个CpG位点，以评估它们的甲基化状态与年龄的相关性。这些位点通过从5至73岁的志愿者采集的72份血液样本和91份唾液样本进行评估。DNA经亚硫酸氢盐修饰后进行PCR扩增和焦磷酸测序，以确定每个CpG位点的DNA甲基化水平。在本研究中，SCGN和KLF14基因座中的某些CpG位点显示出与实际年龄相关的甲基化水平，然而，DLX5中检测的CpG位点与年龄无关。使用52份唾液样本训练集，通过多变量线性回归分析开发了两个年龄预测模型用于年龄预测。这两个模型表现相似，单基因座模型解释了85%的年龄方差，平均绝对偏差为5.8岁，双基因座模型解释了84%的年龄方差，平均绝对偏差为6.2岁。在验证集中，单基因座模型和双基因座模型的平均绝对偏差分别为8.0岁和7.1岁。还使用40份血液样本训练集开发了另一个年龄预测模型，该模型解释了71%的年龄方差。该模型在训练集中的平均绝对偏差为6.6岁，在验证集中为10.3岁。结果表明，SCGN和KLF14中的特定CpG可作为潜在的表观遗传标记物，用于通过唾液和血液样本估计年龄。这些表观遗传标记物在确定嫌疑人年龄对开展调查线索至关重要的案件中可提供重要信息。
