DNA paternity testing principle and identification steps

DNA paternity testing uses the theories and techniques of forensic science, biology and genetics to analyze the genetic characteristics from the similarities of morphological structure or physiology of offspring and parents, and to determine whether parents and children are intimate. DNA paternity testing: also known as paternity testing, is an important part of forensic evidence identification.

DNA paternity testing is a highly specialized discipline. Therefore, for ordinary people, the contents of the professional DNA paternity test report often only understand one result, but the above professional nouns are confusing. Today we will introduce the principle of DNA paternity testing.

The most commonly used identification of parent-child relationships is DNA typing. Human blood, hair, saliva, oral cells, etc. can be used for paternity testing. A person has 23 pairs of 46 chromosomes on the same chromosome. A pair of genes at the same position is called an allele. Generally, one from the father comes from the mother. If it is detected that the allele of a DNA site is the same as the mother, the other should be the same as the father, otherwise there is doubt.

Using DNA for paternity testing, as long as dozens to dozens of DNA loci for detection, if all the same, you can determine the parent-child relationship. If there are more than 3 different loci, you can exclude parent-child relationship. If there are two or two loci, you should consider the gene. The possibility of mutation is added to the detection of some sites for discrimination. The accuracy of the DNA paternity test to negate the parent-child relationship is almost 100%, and the accuracy of the parent-child relationship can reach 99.99%.

DNA (deoxyribonucleic acid) is the atomic substance of cells in the human body. Each atom has 46 chromosomes. In addition, male sperm cells and female eggs each have 23 chromosomes when sperm and egg are combined. These 46 atomic chromosomes create a life, so each person inherits half of the molecular material from the father, and the other half gets it from the mother.

DNA paternity testing is very different from traditional blood testing. It can be tested on different samples including blood, sacral cells, tissue cell samples and semen samples. Because of the blood type, such as type A, type B, type O or type RH, it is more common in the population to distinguish the blood relationship of each individual, but not as effective as the DNA paternity test. In addition to the real twins, the DNA of each person is unique. Because it is so unique, like fingerprints, for paternity testing, DNA is the most effective method. Our results are usually 10 to 100 times more accurate than what is required in court.

DNA paternity testing is currently the most accurate method of paternity testing. If the child's genetic locus is at least 1 inconsistent with the tested man's locus, then the man is 100% excluded from the blood relationship, ie he is absolutely impossible to be the child's father. . If the child is consistent with the parent's position, we can conclude that the parental relationship is greater than 9999%, which proves the blood-related parent-child relationship between them.

DNA paternity testing steps are as follows

First step DNA extraction

Extract the DNA contained in the sample nucleus and then purify it to remove impurities from the sample.

Second step PCR amplification

The Chinese name of PCR is called polymerase chain reaction. The simple step of PCR amplification is to enlarge the fragments we need by enzymatic reaction on the PCR instrument to a degree that can be seen by some special instruments.

The third step after the PCR reaction

This step is mainly to open the double-stranded DNA in the preparation stage of the sequencing instrument detection. The internal standard for some detection is mainly used to mark the length of the detected fragment.

The fourth step is capillary sequencer detection

Due to the charge of DNA by capillary electrophoresis, the electrophoresis speed of different fragments of DNA length is different. The distance of the same electrophoresis time is the same. The different distances of these lengths can be distinguished by the internal standard measurement added at the same time. The software is displayed on the computer for the convenience of the tester to process and analyze the data.

The fifth step analyzes the data issue report

The main reason is that the testers will analyze and summarize the results, and then draw conclusions and reports.

Item number

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specification

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Observation area: 120 × 120 (mm)

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