Department of Forensic Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Department of Forensic Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan; Forensic Science Laboratory, Kyoto Prefectural Police Headquarters, Kyoto, Japan.
Leg Med (Tokyo). 2021 Feb;48:101806. doi: 10.1016/j.legalmed.2020.101806. Epub 2020 Nov 4.
In forensic genetics, a suspect is assigned to a component of a DNA mixture profile, and a probabilistic interpretation is then usually performed. However, it is difficult to determine what types of body fluid the component is from. Previous studies have reported that the fourth exon of the Dishevelled binding antagonist of beta catenin 1 (DACT1) gene is hypomethylated in a semen DNA-specific manner. In the present study, we evaluated whether the DACT1 gene could be effectively used to identify semen in body fluid mixtures and were able to semi-quantify the semen DNA content in mixed fluids. Our results showed that the DACT1 gene was useful in discriminating semen from venous blood and saliva. However, the amount of sperm in semen can affect semen identification. In addition, SI (the semen DNA content index), which we developed, was useful to determine whether the semen compromised majority, almost half, or was in the minority of the components in a mixed fluid. This technique is based on the methylation-sensitive high-resolution melting (MS-HRM) technology, which is time-, cost-, and labour-effective, and could be adopted in routine criminal investigations.
在法医遗传学中，将嫌疑犯分配到 DNA 混合物谱的一个组成部分，然后通常进行概率解释。然而，很难确定该组成部分来自哪种类型的体液。以前的研究报告称，Dishevelled 结合 β 连环蛋白 1（DACT1）基因的第四外显子以精液 DNA 特异性方式呈低甲基化。在本研究中，我们评估了 DACT1 基因是否可有效地用于鉴定体液混合物中的精液，并能够对半定量混合液中的精液 DNA 含量。我们的结果表明，DACT1 基因可用于区分精液与静脉血和唾液。然而，精液中的精子数量会影响精液的鉴定。此外，我们开发的 SI（精液 DNA 含量指数）有助于确定精液在混合液中的组成部分中是否占多数、几乎一半还是少数。该技术基于甲基化敏感高分辨率熔解（MS-HRM）技术，该技术省时、省钱、省力，可用于常规犯罪调查。
