A method for analyzing mixed sample DNA based on indel-snp linkage relationship

Abstract

The invention relates to a method for analyzing mixed sample DNA (Deoxyribose Nucleic Acid) on the basis of an INDEL-SNP (INDEL and Single Nucleotide Polymorphism) linkage relationship, and belongs to the technical field of forensic detection. The method comprises: (1) carrying out RT-PCR (Reverse Transcription-Polymerase Chain Reaction) amplification on the mixed sample DNA to obtain a PCR product containing two linkage sites of INDEL and SNP; (2) carrying out parting on the SNP contained in the amplification product obtained in the step (1). The method disclosed by the invention has the following advantages that: a designed INDEL-SNP primer has the species specificity, is suitable for forensic detection, and can be used for DNA detection analysis of forensically common mixed stains no matter whether the mixed strains are formed by the cells of a same type or the cells of different types; the method also can be used for monitoring transplant ingredients of peripheral blood after a bone marrow transplantation operation or other organ transplantation operations, and identification time limit is also advanced greatly.

Description

technical field [0001] The invention belongs to the technical field of forensic medicine detection, and in particular relates to a method for analyzing mixed sample DNA based on INDEL-SNP linkage relationship. The analysis of mixed sample DNA (that is, mixed spots) includes confirming mixed spots and performing individual identification on mixed spots. Background technique [0002] Mixed samples of two or more individuals can be seen in the following situations: (1) Forensic mixed samples include mixed spots of blood samples, saliva spots, semen spots, vaginal secretions, etc. from multiple individuals; (2) patients undergoing bone marrow transplantation Or peripheral blood samples or organs after organ transplantation; (3) detection of early mutations in tumor patients or heterogeneity of tumors; (4) fetal samples mixed in peripheral blood of chimeric individuals or pregnant women, etc. With the development of DNA detection technology, the detection sensitivity of DNA mixed...

AI Technical Summary

Problems solved by technology

But this technology has the following disadvantages (1) instruments and reagents etc. make the method expensive and require professional analysis, which is difficult to popularize; (2) compared with STR analysis, this method can obtain all information on a DNA chain, and the polymorphism is greatly reduced. Improvement, the sensitivity is improved compared with the STR method (can detect 1% DNA), but there is a certain error rate (generally within 2%), forensic analysis requires accuracy to be the first, any base sequence Any misinterpretation will cause irreparable losses to the prosecution

Therefore, the method needs to be carefully evaluated for forensic analysis.

[0007] 3: SNP analysis: There are many kinds of SNP analysis techniques. Since the polymorphism of a single SNP is much lower than that of STR analysis, direct sequencing or electrophoresis is rarely used to detect mixed spots; INDEL can be regarded as a special SNP. At present, there are corresponding kits in foreign countries. In addition to forensic polymorphism analysis, it is also used to analyze the composition ratio of peripheral blood DNA after bone marrow transplantation, but there is no forensic mixed spot analysis.

Because it uses the information of a single SNP, the polymorphism is low, and there is a certain degree of false positives, the experimental conditions are very strict, and it is rarely used in forensic mixed spot analysis and DNA analysis after bone marrow transplantation

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