Method for analyzing mixed sample DNA

Abstract

The invention discloses a method for analyzing mixed sample DNA. The mixed sample DNA is analyzed with a method combining INDEL with Microhaplotypes; in other words, father source or mother source DNAof an individual is sorted through differential amplification of the INDEL, and then individual distinguishing is conducted through the Microhaplotypes on DNA molecules; the method is named a DIP-Microhaplotypes method. The method has the advantages that analysis of a mixed DNA sample of two samples and detection of mixed stain sensitivity mainly depend on the INDEL, following detection of SNP isrelated to a detection means, and mixed stains can be successfully analyzed and used for excluding or confirming the individual; an INDEL-SNP primer has species specificity and is suitable for forensic medicine detection; the method is possibly used for monitoring transplant ingredients in peripheral blood after a bone marrow transplantation operation or other organ transplantation operations; the method is possibly used for all cases where individuals need to be distinguished when the mixed sample is involved.

Description

technical field [0001] The invention relates to the technical field of DNA typing, in particular to a method for analyzing mixed sample DNA. 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 samples has been greatly improved, but it is still not possible to distinguish each individual that constitutes the mixed spot. [0003] The commonly used DNA techniques for detecting mixed plaques can be roughly...

AI Technical Summary

Problems solved by technology

[0006] (1) The analytical sensitivity for mixed spots is very low, and mixed spots with a composition content lower than 5-10% cannot be detected;

[0007] (2) STR analysis belongs to post-PCR analysis, although dominant peaks and non-dominant peaks can be analyzed, but due to the platform effect in the later stage of PCR, the method is not quantitatively accurate;

[0008] (3) The DNA of the mixed spot produces multiple peaks at each STR site, and it is impossible to determine the individual among them. Generally, the exclusion method is used to exclude the individual, and the likelihood ratio calculation is more complicated.

[0010] (1) Instruments and reagents make the method expensive and require professional analysis, making it difficult to popularize;

[0011] (2) Compared with STR analysis, this method can obtain all the information on a DNA chain, the polymorphism is greatly improved, and the sensitivity is improved compared with the STR method (can detect 1% DNA), but there are certain errors rate, needs to be carefully evaluated for forensic analysis

[0012] 3. SNP analysis, there are many kinds of SNP analysis techniques, because the polymorphism of a single SNP is much lower than that of STR analysis, therefore, direct sequencing or electrophoresis methods are 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 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, and the requirements for experimental conditions are very strict, so it is rarely used in forensic mixed spot analysis and DNA analysis after bone marrow transplantation

Images