Development And Validation Of 35 InDels Fluorescence Multiplex System And Genetic Background Explorative Analysis Of Three Ethnic Minorities In Chinese Xinjiang Area

BackgroundIn forensic applications,one of the difficulties is the detection of degradation materials.Because the length of amplified fragment of STR is more than 300bp,and the valid genome typing result can’t be obtained.Recently,Insertion/Deletion(InDel)polymorphism has been used in forensic filed due to it combines the advantages of STR and SNP,besides the length of InDel is short,which made it suitable for degradation materials.Currently,the human identification InDel panels were mostly designed aiming for European populations.In this research,we tried put forward an InDel multiplex system applied to the human identification word in China.China is a multi-ethnic country,and Xinjiang Uygur autonomous region located in the northwest China with different populations settlement there.Studying the polymorphism of ethnic minorities in Xinjiang is conducive to revealing the origin of ethnic groups in the northwest of China,the migration and the integration of ethnic groups.In addition,understanding the genetic background of different ethnic groups and genetic polymorphisms of various ethnic groups can play a preliminary role in general cases in forensic practice,such as providing clues in complex and difficult cases;applied for population stratification studies,provide evidence for the identification of missing persons.It is the basis for the evaluation of mixed ethnicity characteristics in forensic anthropology research as well.Method and resultsFirstly,we screened 35 InDel loci in the database,and the traditional PCR amplification and capillary electrophoresis platform combined with four-color fluorescence parallel detection technology were used by considering the characteristics of its length polymorphism and its application in the grassroots forensic laboratory.For the newly constructed 35 InDel systems,including reproducibility and accuracy,sensitivity,specificity,degradation samples,stability verification,and mixed DNA validation.In terms of forensic efficacy,the forensic parameters such as heterozygosity and personal recognition ability were used to make a scientific assessment of the individual identification ability of the whole system.In addition,based on the Fsr value,the In value combined with the allele frequency distribution,the system was evaluated for global population differentiation efficiency and potential ancestral information site exploration.In terms of the genetic background of ethnic minorities in Xinjiang,we selected the Hui population due to it is one of the largest minorities in China.And the Eurasian mixed ethnic Uighurs and the Kazaks were choed as the research objects as well.The different genetic markers such as InDel,mitochondrial DNA and SNP were conducted the studies based oncapillary electrophoresis platform and the next generation sequencing platforms for deep sequencing.The genetic structure diversity and genetic background of these three ethnic groups were explored using forensic statistical analysis methods including Nei’s genetic distance,STRUCTURE analysis,principal component analysis,and phylogenetic tree.ConlusionIn this study,a set of 35 InDel multiplex amplification systems were put forward for human identification of degradated materials,and this new assay was efficient,stable and economical.Besides,we established a method for stratification of population structure based on different genetic markers and capillary electrophoresis platforms.In addition,we also accumulated experience in processing massive data of second-generation sequencing platforms,and established a prediction of the proportion of ancestral components of unknown individuals.The model and the method of finely portraying the genetic background of the mixed population were set up as well.To reveal the genetic background of Hui Uygur and Kazaks,our self-developed 35 InDel systems,165 SNP-AIMs,and mitochondrial DNA were used.The genetic background of three ethnic minorities in Xinjiang was as follows,Xinjiang Hui nationality had close genetic relationship with most ethnic groups in China;Xinjiang Uygur and Kazakh are mixed Eurasian populations which the Uighur European-East Asian mixed ratio is about 1:1,and the Kazakh European-East Asian ratio is about 37:62.