The unborn fetus can be identified by paternity test. Generally, pregnant women can extract villi or amniotic fluid for identification. The optimal extraction time of villi is 8- 10 weeks, and the optimal extraction time of amniotic fluid is 16-24 weeks. You can check the pregnancy time by B-ultrasound.
Paternity identification is the main part of forensic material evidence identification, which uses the theories and techniques of forensic medicine, biology and genetics to analyze the genetic characteristics and judge whether the relationship between parents and children is biological or not from the similarity of morphological structure or physiological function between offspring and parents. Simply put, it is to identify the genetic relationship between parents and children through blood type or DNA testing. If parents' blood, hair, saliva, oral cells and bones do not exist, relatives can be identified.
Paternity identification can be carried out in qualified medical institutions. The steps of DNA paternity experiment are as follows:
Step 1: DNA extraction
The DNA contained in the sample nucleus is extracted and then purified to remove impurities in the sample.
Step 2: PCR amplification
The Chinese name of PCR is polymerase chain reaction. Simply put, the step of PCR amplification is to make a large number of copies of the required fragments on the PCR instrument through enzymatic reaction, and enlarge them to the extent that some special instruments can see them.
Step 3: Post-PCR reaction
This step is mainly the preparation stage of ABI sequencer detection. Open the double-stranded DNA and add some internal standards for detection, which are mainly used to mark the length of the detection fragment.
Step 4: Capillary sequencer detection.
Because DNA is charged, capillary electrophoresis has different electrophoresis speeds for different fragments of DNA. Under the same voltage and electrophoresis time, the swimming distance is different. These different distances can be distinguished by the internal standard measurement added in the early stage, and displayed on the computer through certain software, which is convenient for inspectors to process and analyze the data.
Step 5: Analyze the data and issue a report.
It is mainly for inspectors to analyze, summarize and calculate the obtained results, and then make appraisal conclusions and reports.