Study On InDel Ancestry Inference Microfluidic Chip Genotyping Panel

Short tandem repeat（STR）genetic markers are one of the commonly used technical methods for forensic DNA genotyping to type biological samples,to identify or exclude criminal suspects.However,when the STR typing of the inspection material is inconsistent with the suspect’s typing or the DNA database search results in no results,the case investigation often falls into a passive state.At this time,the use of polymorphic markers with large differences in allele frequency distribution among different populations,that is,ancestry information markers,to infer the Ancestry origin of DNA donors can provide directions for case investigation.The conventional forensic DNA genotyping process is complex,time-consuming and labor-intensive,and it is difficult to meet the needs of the public security for on-site rapid DNA genotyping.The rapid DNA genotyping system based on microfluidic chip technology integrates all DNA genotyping processes,which solves the above problems well.Based on the previously established38-plex InDels panel,this study evaluated the ancestry inference efficiency of the panel.For the first time,the InDel ancestry inference panel was combined with the rapid DNA genotyping system to construct a set of InDel ancestry inference microfluidic chip genotyping panel for the domestic rapid DNA genotyping system.At the same time,the microfluidic chip genotyping panel was verified and evaluated,and the rapid integrated genotyping and ancestry inference of biological samples were finally realized.The results of the population genetic structure study showed that the 38-plex InDels ancestry inference panel has good inference efficiency,and can accurately infer the information of individual ancestry components and the genetic relationship of the population.The PCR amplification reagents of the microfluidic chip genotyping panel are stored by vacuum freezedrying.The freeze-dried reagents can still maintain a good molding effect after 7 weeks of storage,and can accurately type the buccal swab samples.The complete InDel profiles can be obtained more than 5 ng of template DNA input.The best collection of buccal swabs was the donor who performed 8 swipes inside of cheek.The best collection of dried blood spot samples was 6 pieces（Φ=2 mm）.The microfluidic chip genotyping panel was concordant with traditional methods,with 95.65% success rates and 98.85% concordance rates for 138 testing samples.The fully integrated genotyping of buccal swabs,blood cards,saliva cards and other samples can be completed within 2 hours,which can accurately infer the ancestry information of samples,meet the needs of on-site DNA genotyping,and can be used for actual casework.