东亚人群毛干蛋白中单氨基酸多态性检测方法建立与个体识别应用

目的 毛干是案件现场常见的生物物证,目前缺少有效的个体识别方法而未能在案件调查和法庭诉讼中发挥作用。毛干蛋白质组中的单氨基酸多态性（SAP）蕴含着个体遗传差异信息,可应用于个体识别。方法 为研究毛干物证SAP个体差异,本文使用离子液体对12份2 cm长的毛干样本（6人,每人2根）经过前处理后,进行LC-MS/MS质谱检测,分析毛干中的蛋白质组成。然后利用自建的东亚人群SAP蛋白质序列数据库,对质谱数据进行搜库分析,依据自建的SAP与SNP对应注释表信息,推导出SAP对应的nsSNP分型,并且与外显子测序nsSNP结果比较,进而验证SAP检测的准确性。最后,利用验证准确的SAP分型进行随机匹配概率的计算。结果 12份样品共计获得321个SAP,每个样本平均为（131±17）个。6人的随机匹配概率数值范围为1.4×10^-4~1.0×10^-9。结论 本文建立了东亚人群毛干蛋白中SAP检测方法,并验证了个体识别应用的能力,为法庭科学中毛干个体识别提供了有力的工具和新的思路。

Establishment of Single Amino Acid Polymorphism Detection Method for Hair Shaft and Individual Identification Application in East Asian Population

Objective Hair shaft is one kind of common biological evidences at the crime scene. However, it fails to play an important role in the crime investigation due to lack of effective method of individual identification. The single amino acid polymorphisms (SAPs) in the hair shaft proteome contain information of individual genetic differences.Methods In order to study SAPs in the hair shaft, the proteome of single 2 cm hair shaft samples (6 people, 2 hairs per person) were extracted using ionic liquid following with LC-MS/MS detecting. The protein composition of the hair shaft was analyzed. A custom SAP protein sequence database was built for East Asian population as the searching database. Based on the custom SAP and SNP corresponding annotation table information, the nsSNP profiles were imputed corresponding to SAP. The accuracy of SAP was verified by comparing the imputed nsSNP profiles from SAP with nsSNP profiles obtained from the whole exome sequencing. The validated SAPs were used to calculate the random matching probability.Results In 12 samples, 321 SAPs were obtained, with an average of (131±17) for each sample. The value of random matching probability for 6 people ranged from 1.4×10^-4 to 1.0×10^-9.Conclusion In this paper, a method for detecting SAP in hair shaft proteins of East Asian populations was established, and the ability of individual identification application was verified, which provided a powerful tool and new ideas for individual identification of hair shaft in forensic science.