Basic Information
Chinese name: Paternity test
Definition: It is the main component of forensic evidence identification
Identification application: criminal, civil, household identification, etc.
Modern methods: blood type testing, DNA verification and more
Identify the reason
The main reason for the paternity test: with the development of science and technology, and the change of traditional family concept, the level of modern biotechnology coincides with the demand. Due to liberalization and people's openness to gender relations, contempt for ethics, and changes in life style, many couples worry about whether the child is their own after marriage. A woman who has had a sexual relationship with one another asks for a pregnancy test in order to find out who the real father of the child is.
Forensic paternity test
In inheritance disputes, it is necessary to determine whether there is a biological relationship;
Identification of rapists;
claim abducted children;
Unmarried pre-natal settlement, over-birth settlement, unable to provide birth certificate;
The identity of the victims (air crash, tsunami, etc.) cannot be identified; custody disputes;
Personal paternity test
Suspect that the child is not biological;
Suspected that the hospital delivery room or nursery room misplaced the newborn;
Separation of family members to identify relatives;
Paternity test also includes: kinship test (paternal or maternal), immigration test, etc.
According to the different purposes of identification, paternity identification can be divided into forensic identification and personal identification.
1. The personal paternity test itself is not public, so the test client has the right not to provide any documents. Samples can be taken by themselves and sent to professional appraisal institutions, and the appraisal results are only provided to the appraisal client. The identification results can be used as evidence in civil proceedings.
2. The judicial paternity test is completely open, and must be approved by the three parties of the principal, the mother and the child. They must be present face-to-face, and bring all relevant valid documents including ID cards, household registration books, etc. The identification results can be used for judicial purposes (registration of household registration, immigration, lawsuits, etc.), and can also be used as evidence in court.
1) Forensic identification can only be applied to litigation activities, and is a scientific identification activity initiated by a judge during a specific litigation and trial process. In other words, those who do not participate in litigation activities, that is, do not file a lawsuit in court, do not need to do a judicial paternity test; if a lawsuit is filed, after the lawsuit is brought to the court, the appraisal initiated by the court is called forensic appraisal.
2) Forensic appraisal activities must be conducted in accordance with the Procedure Law and relevant judicial interpretations, and the appraisal conclusion that the procedure is illegal cannot be used as appraisal material.
Judicial paternity test refers to a type of test that requires the test report to be provided to judicial institutions such as courts, public security organs, notary offices, and entry-exit administration offices. The judicial paternity test report has legal effect and can be used as evidence.
The judicial paternity test report of the appraisal center is applicable to mainland China, Hong Kong, Macao, Taiwan and other countries and regions (except for certain countries and regions due to political system restrictions), and can be used for litigation, notarization abroad, visa application, household registration, etc. Forensic identification must be done: the identification subject is legal, the identification material is legal, the identification procedure is legal, the identification steps are legal, and the identification methods and standards are legal. Forensic identification must be issued by a relevant agency (public security organ, people's procuratorate, people's court), and the identification completed after a series of judicial notarization procedures is called forensic identification and is only used as court evidence. The identification conclusion must be cross-examined by the court. to be valid. The characteristics of judicial paternity test: the acceptance procedure of judicial paternity test is relatively strict to ensure the accuracy, truth, fairness and effectiveness of the test results.
(1) The person to be authenticated must come to the center in person to handle the real-name entrustment;
(2) The person to be authenticated must provide his true and valid identity document;
(3) The appraiser must promise that the information provided is true and valid;
(4) Our appraisal center carefully checks the identity information of the appraiser and takes pictures on the spot;
(5) The paternity test samples must be collected by the staff of the center, and a notary must be present when necessary.
3) More than 80% of the paternity tests have not started forensic appraisals, which are all personal appraisals.
Personal identification is a biological identification of an individual's genetic genes by an identification agency. In the sampling process, there is no need for a power of attorney issued by the public inspection law, nor does it completely require the applicant to provide ID cards and other certificates and consent. It can be used as one of the evidences, but the identification process and the accuracy of the identification results are consistent with forensic identification.
individual identification
It is generally used in criminal cases to identify whether DNA information belongs to the same person.
kinship identification
Genetic theory has confirmed that half of each child's genomic DNA comes from one parent. At present, the kinship identification carried out by the forensic material evidence profession includes the following categories:
1. Conventional biological blood relationship identification: this is the most in-demand type of paternity relationship identification, including parent-child tripartite (also known as triplet), father-son (or mother-son) both (also known as doublet) Paternity test. The accuracy of such identification can reach 99.999999%.
2. Intergenerational kinship identification: This type of identification refers to confirming the kinship between great-grandparents, grandparents, and great-grandchildren (great-granddaughters) and grandchildren (granddaughters). It also includes simple paternal kinship identification, such as to confirm the kinship between great-grandfather, grandfather, and great-grandson, grandson, and pure maternal kinship identification, such as to confirm the kinship between great-grandmother, grandmother, granddaughter, and great-granddaughter. .
3. Difficult kinship identification: In addition to the above two categories, there are some more difficult kinship identifications, such as the identification of compatriots (brothers, siblings, siblings, sisters) and cousins whose parents are suspected (no), Identification of kinship between uncles and nephews, between aunts and nieces, and between uncles and nephews (nieces).
Identification principle
The theoretical basis for judging biological relationship is Mendel's law of segregation. According to this law, when gamete cells are formed, paired alleles separate from each other and enter their respective gamete cells. The sperm and egg cells are fertilized to form offspring, and the two genomes of the child come from the mother and the father; therefore, the same pair of alleles is one from the mother and one from the father. If the identification result conforms to this rule, the biological relationship is not excluded, if not, the biological relationship is excluded (except for variation). In most cases, the parent-child relationship is known, requiring identification of the hypothetical parent-child relationship. At this time, from the comparison of the genotypes of the mother and the child, it is possible to determine the gene (the biological father gene, OG) that may be derived from the father in the child's genes. Then observe the genotype of the hypothetical father, and if there is no biological father gene, the biological relationship between the hypothetical father and the child can be ruled out. If it is assumed that the father also has the biological father gene, the results cannot rule out the biological relationship of the assumed father. In a case, if the mother is FGA-22/23 type and the child is 22/25 type, it can be determined from the comparison that the biological father gene is FGA-25. In this case, parent 1 is assumed to be FGA-22/24; parent 2 is assumed to be 24/25. Among them, it is assumed that father 1 does not have the biological father gene 25, so his biological relationship with the child can be excluded; in contrast, it is assumed that father 2 has a biological relationship with the child because he has FGA-25.
Identification step
The steps of DNA paternity test are as follows:
The first step: DNA extraction Extract the DNA contained in the sample cell nucleus, and then carry out certain purification to remove impurities in the sample.
The second step: PCR amplification The Chinese name of PCR is polymerase chain reaction. In short, the step of PCR amplification is to make a large number of copies of the fragments we need on the PCR machine through enzymatic reaction, and amplify them to pass the enzymatic reaction. The extent to which certain specialized instruments can see.
The third step: post-PCR reaction This step is mainly the preparation stage for the detection of the ABI sequencer. The double-stranded DNA is opened, and some internal standards for detection are added, which are mainly used to mark the length of the fragments to be detected.
Step 4: Capillary sequencer detects that due to the charge of DNA, by capillary electrophoresis, the electrophoresis speed of different DNA fragments is different. Under the same voltage and the same electrophoresis time, the swimming distance is different, and these distances are different in length. It can be distinguished by the internal standard measurement added in the early stage, and at the same time, it can be displayed on the computer through certain software, which is convenient for the inspection personnel to process and analyze the data.
Step 5: Analyze the data and issue a report. The main reason is that the testing personnel will analyze, summarize and calculate the obtained results, and then draw an identification conclusion and report.
Identify applications
criminal case
1. Rape causes pregnancy, and the criminal suspect needs to be identified;
2. Unnamed corpses or skeletons that are highly corrupt and need to be identified;
3. The paternity test of the abducted children;
4. In the event of death in a traffic accident, the relatives need to claim the body and seek compensation.
civil case
1. Handle immigration;
2. Child household registration;
3. Property inheritance disputes;
4. Suspected that the baby has been exchanged;
5. Bloodline identification of superborn children;
6. Bloodline identification of children born out of wedlock;
7. Bloodline identification of separated children;
8. The man wants to confirm whether the child is biological;
9. Adopted children seek biological parents;
10. Help find lost family members;
11. Helping women obtain child support payments from the biological father of the child;
12. Help parents to obtain custody and visitation rights of their biological children;
13. Bloodline identification of test-tube babies, to identify whether there are laboratory errors in test-tube babies obtained by in vitro fertilization;
14. In other cases, a DNA paternity test is required.
Account identification
The family paternity test is a very serious matter. It is also a paternity test derived from China's unique household registration management system. A paternity test is on.
1. In the following cases, a paternity test needs to be done before registering:
1. No birth certificate. For various reasons, the child was not born in a hospital qualified for obstetrics and gynecology, or was not born in a hospital, so there was no standardized birth certificate, and a paternity test was required when registering. Or have a birth certificate, but the parents' names on the birth certificate are inconsistent with the names on the ID card and household registration book, and a paternity test certificate is required.
2. Because the child is abducted, sold, lost, and then recovered through various means, the household registration needs to be registered with the biological parents, and the paternity test report is required.
3. If the child is born out of wedlock, the existing legal documents cannot prove the biological parental relationship of the child. Or in a single-parent family, the child's household registration needs to be transferred from the father's side to the mother's side, or from the mother's side to the father's side, and a paternity test is required.
4. Abandoned children go home. If the child is adopted and needs to be adopted back, or because of avoiding family planning, the child's household registration needs to be transferred to the biological parents' name under the name of another person, and a paternity test needs to be done.
5. Special regulations of the department, because some departments are afraid that other industry personnel will enter special industries when recruiting and recruiting workers, parents and children in the industry need to prove parent-child relationship when recruiting workers. For example, the Zhengzhou railway system requires a paternity test certificate.
6. If the adopted child is registered in the household, it is necessary to prove that the child and the adoptive parents are not biologically related.
2. Procedures required for the family paternity test: The family paternity test belongs to the process of providing evidence by the related parties of the family, so the identification certificate only needs to be provided by the identification party:
1. A certificate that can prove the identity of the person being authenticated: such as ID card, household registration book, military identity certificate, birth certificate, etc. Those who do not have the above certificates need to apply for an appraisal certificate from the people's government at or above the township, the sub-district office, or the police station of the public security.
2. The person to be authenticated must go to the judicial authentication center to collect blood to participate in the authentication and complete the identity verification work. Mainly verify identification, leave fingerprints, and take photos.
3. If it is really inconvenient for the appraiser to go to the forensic appraisal center for sampling, etc., you can contact the staff of the forensic appraisal center to sample and verify the identity.
3. Select the identification agency. There are many institutions that do paternity testing, but household paternity testing belongs to the category of forensic testing. Therefore, when choosing a testing agency, you must have a "". The parent-child testing report must be valid nationwide and recognized by the public security, judicial and other departments across the country. It is necessary It also requires an internationally recognized forensic identification agency to do identification (for example, if the child is abducted to a foreign country or Hong Kong and other regions), etc.
4. Persons who participate in the appraisal of the family paternity test: only considering the needs of the family, it can be a father-son (female) or mother-child (female) appraisal, and the family can be registered with the appraisal conclusion. However, due to the genetic mutation factors in the paternity test and many factors of the household registration, it is best to do the paternity test with three parents and children (female).
5. The identified person has transfused the blood of others within six months, or has undergone bone marrow transplantation within two years, and cannot draw an accurate conclusion. Those who need identification should avoid the above time.
original method
Appearance comparison
Due to genetic reasons, father and son, mother and son, brothers and sisters generally have some similarities in appearance, skin color, etc. It is probably the most primitive method to determine parent-child relationship through the comparison of appearance, but this method is only a guess , judgment, as a reference.
drop bone test
Bone drop test is to drop the blood of the living on the bones of the dead. If the blood can penetrate into the bones, it is concluded that the living and the deceased have a blood relationship, otherwise there is no. The "Biography of Kuaiji Xianxian" written by Xie Cheng, a native of Wu State during the Three Kingdoms period, records the case of claiming the eldest brother's corpse with blood dripping from his brother's skeleton; The case of testing relatives on the father's bones; in the Song Dynasty, Song Ci, a famous forensic scientist, included the method of testing relatives on the bones in the "A Collection of Injustices". From a modern point of view, this method is not scientific, but it pioneered The first of its kind to identify blood relationship by blood type.
blood test
The blood drop test is also called the combined blood test, which means that the blood of a child and the blood of an adult are put together. This method of identifying samples was recorded in the forensic works of the Song Dynasty in China. There is no scientific basis for this method. The blood of parent-child relationship may not necessarily fuse, but the blood of non-parent-child relationship may fuse.
modern approach
blood type test
A blood type test is used to determine paternity by comparing blood types. According to Mendel's law of inheritance confirmed at the end of the 19th century, people realized that the blood type of human beings is passed on to the next generation according to the genetic genes, so the children born to the parents of a certain blood type also have the corresponding blood type, which laid the foundation for the blood type identification of the parent-child relationship. The main blood group systems used for blood group testing to identify parentage are:
ABO blood group system
MN blood group system
Rh blood group system
Ss blood group system
hp blood group system
The more blood type systems tested, the higher the accuracy. If the results of the blood type test indicate that there is no genetic relationship, the conclusion of denying the parent-child relationship can be made. In the 1970s, it was discovered that white blood cell antigens could be used for paternity testing with an accuracy of 80%. Combined with blood type testing, a higher degree of accuracy can be achieved.
Chromosomal polymorphism
In the 1980s, medical scientists pioneered the use of chromosomal polymorphisms to identify paternity. Such as: satellite enlargement, duplication or absence, fluorescence intensity variation of specific granule region, etc.), this polymorphism can be inherited. This technology uses its shape to identify parent-child relationship, which depends on the subjective judgment of technicians, and its accuracy is not satisfactory.
DNA identification
The most commonly used method for identifying paternity is DNA typing. Human blood, hair, saliva, oral cells and bones can all be used for paternity testing, which is very convenient. A person has 23 pairs (46) of chromosomes, and a pair of genes at the same position on the same pair of chromosomes is called an allele, usually one from the father and one from the mother. If alleles at a DNA locus are detected, one is the same as the mother and the other should be the same as the father, otherwise there is doubt. Using DNA for paternity testing, as long as a dozen to dozens of DNA sites are tested, if all of them are the same, the paternity relationship can be determined. If there are more than 3 sites that are different, the paternity relationship can be excluded. If the points are different, the possibility of gene mutation should be considered, and some loci detection should be added to identify them. DNA paternity test, the accuracy rate of denying parent-child relationship is nearly 100%, and the accuracy rate of affirming parent-child relationship can reach 99.99%.
The DNA paternity test mainly determines the stability of somatic cells by the following characteristics: the DNA of the blood, saliva, semen and various organs and tissues of the same individual is consistent, and is unchanged for the same healthy person for life. This is the most basic premise . Individual high specificity: The differences in the genetic nature of DNA molecules of different individuals determine that the same restriction enzyme digests genomic DNA, and the number and length of allele fragments of one individual and another cannot be the same. produce individual-specific DNA. Inheritance according to Mendelian inheritance law: Through a large number of family investigations, it has been proved that all allele bands in the offspring DNA can be found in the parents' DNA, and the transmission of fragments conforms to the Mendelian inheritance law.
paternity index
The ratio of the probability that the father provides the father's genes to become the child's biological father and the probability that a random man provides the biological father's genes to become the child's biological father is called the paternity index (PI). The former possibility is assumed to be X; the latter possibility is assumed to be Y. The hypothetical Father 2 genotype in the above example is a 24/25 heterozygote, and the probability that he provides the biological father gene FGA-25 is 1/2, that is, X=1/2. The chance of a random man providing the paternal gene FGA-25 is the frequency of that gene, ie Y=0.0958. Therefore, the PI value for this example is 0.5/0.0958=5.22. If it is assumed that Father 2 is indeed the biological father of the child, no matter how many sites are detected, the biological relationship between him and the child will not be ruled out. At all tested sites, one PI value can be calculated for each site. The cumulative PI value of a point is equal to the product of the PI values of the individual loci, provided that there is no genetic linkage between the detected loci.
The combination of triplet genotypes can be summarized into three principles:
(1) When the father is assumed to be homozygous, X=1; when the father is assumed to be heterozygous, X=1/2, but when the heterozygote assumes that both of the father's two genes may be biological father genes, X=1.
( 2 ) When only one biological father gene is involved, the Y value is equal to the frequency of the biological father gene.
(3) If two biological father genes are involved, the Y value is the sum of the frequencies of the two biological father genes.
common problem
1. What is a DNA paternity test? 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 When sperm and egg combine. These 46 atomic chromosomes make a life. Therefore, each person inherits half of the molecular material from the biological father, and the other half is obtained from the biological mother. The DNA paternity test is very different from the traditional blood test. It can be tested on different samples including blood, parotid cells, tissue cell samples and semen samples. Due to the blood type such as type A, type B, Type O or RH, which are more common in the population, are less effective than DNA paternity tests for identifying each person. Except for true twins, each person's DNA is unique. Because it is so unique, it's like a fingerprint , for paternity testing, DNA is the most effective method.
2. How accurate is the DNA paternity test? The DNA paternity test is currently the most accurate type of paternity test. If the DNA patterns of the child and the test man do not match on one or more of the DNA probes, the test man will be convicted. 100% exclusion, i.e. he is 0% likely to be the biological father. He cannot be the biological father of the child. If it is the mother and the DNA pattern of the child and the tested father exactly match, then a probability of 99.97% or greater can be calculated. This result proves that he is, in fact, fully proving the biological father of the child. Most US courts accept a 90% probability as proof of biological paternity.
3. Is there a certain age for a child to receive a DNA paternity test? There is no age limit for a DNA paternity test. The traditional blood type test requires a child to be at least 6 months old. Also, a large blood sample is required, usually two A large teaspoon or more. This method is more difficult to apply to children. In contrast, a DNA paternity test requires only a few drops of blood (about 1/4 or 1/2 teaspoon), or gill cells from an oral smear. This small amount of blood or oral test makes the DNA test even Performed on a newborn or small child. Since DNA is formed during conjugation, testing can be performed using Chorionic villi Sampling/CVS or amniocentesis methods even before the child is born. Paternity tests can be collected by funeral home workers on deceased persons When a person is deceased or missing, it is also possible to rearrange his or her DNA organization on his or her blood relatives.
4. Can a paternity test be performed without the participation of the mother? Yes. DNA paternity testing is very effective, even in the absence of the mother. With or without the participation of the mother, the DNA of the child and the man being tested is If the tissue arrangement does not match, then the tested person is 100% excluded as the biological father. If the tissue arrangement matches, then we can calculate a 99.95% or greater probability of biological fatherhood. Individuals who bring underage children to the test, bring identification documents and sign a A form about his/her legal right to bring the child for testing.
5. Is the buccal swab accurate? Another alternative to testing blood is a sample collection method called buccal swab. Since DNA is present in every cell in the body, it is collected using a swab method. The accuracy of the test results obtained from the sample is the same as that of the blood sample. When collecting the sample, use a cotton swab to gently wipe the child's mouth, and the DNA can be extracted from it. This procedure is not compulsory and painless, and is most suitable for children. Since DNA is extracted by this method, there are more steps that can be used in adults. Blood is taken from the body and the oral swab test is used to obtain a sample on the child. Adults can also choose to use the oral swab test.
6. Can the tested people be distributed in different cities? No problem at all.
7. Do I need a hospital certificate or a lawyer's letter to do a DNA paternity test? Not necessarily..
8. Can the paternity test be done before the child is born? Can DNA test be used to test the paternity before the child is born? To be performed within 14 to 24 weeks of pregnancy. Any kind of surgery to be performed by an OB/GYN doctor.
9. The principle and procedure of DNA paternity test DNA is extracted from a few drops of blood, gill cells or cultured tissue fibers. The DNA sample is cut into small pieces with the element, put into the gel, and the DNA is pushed by the electrophoresis tank. The isolated genes are placed on a nylon membrane, and special DNA probes are used to search for genes. The same genes will be condensed into one, and then, using a special dye, under the environment of X-ray, it will be displayed by The DNA probes are condensed into one black bar code. The naked eye bar code of the child is very special - half match the mother's and half match the father's. This process is repeated several times, each probe is used to find Different parts of the DNA are mapped into unique barcodes, and with several sets of different probes, more than 99,95% paternity probability or resolution can be obtained.
10. Could you please explain the result of the paternity test that the child will have one stripe that is the same as the biological mother and another stripe that is the same as the father to be confirmed No. 1 (AF1), who is the biological father; the excluded man (AF2), who is not the same as the child. No identical barcodes. Positive paternity relationship: The probability of paternity is greater than 99.99% or greater than the probability of biological father (legally proven to be biological father) Negative paternity relationship: Three or more gene loci do not conform to the law of inheritance (100% Excluding the biological father) Due to the large domestic population base, it is generally recommended to use more than 20 STR loci for comparison to draw correct conclusions.
sample collection
The method of collecting blood samples
1. Prepare alcohol cotton balls, blood collection needles, medical sterile gauze, and paper envelopes in advance before blood collection.
2. When taking blood, first disinfect the blood collection site with alcohol cotton balls, and disinfect the blood collection needle. Take five drops of thumb-sized blood and drop them on medical gauze.
3. The blood of adults and children should be dropped on different gauze, and marked (parents and children, etc.) to record the collection date.
Precautions:
1. Bloodstains can be collected from ear blood or fingertip blood, and infants can be collected from heel blood.
2. Bloodstains should be dried naturally on the desktop, and should not be heated or exposed to the sun.
3. Blood samples from different people should not be in contact with each other. They should be placed in different kraft paper envelopes, and the envelopes should be clearly marked.
2. Nail collection method Sampling method
1. Before sample collection, the person providing the sample should first remove the dirt in each nail (toothpicks, etc.), then wash hands with clean water and dry them with disposable paper towels or disposable gauze;
2. The sampling personnel should also wash their hands and wear gloves before sampling;
3. Use nail clippers or scissors (clean with water or sterilize with alcohol before each use, so as not to leave the DNA of the former) to reduce the free edge of the nail, and then place it on the white paper prepared in advance;
4. The closer the nails are to the inside (closer to the finger flesh), the better. After cutting, wrap them in clean white paper (do not use plastic bags to seal them). At least 3 nails are required;
Precautions:
1. When collecting the sample, the skin of the person other than the sample should not directly touch the fingernail;
2. After drying in the shade, put it in a paper envelope, do not wrap it in plastic wrap or plastic bag, so as not to affect the quality of the test due to mildew;
3. After the sample extraction is completed, mail it to the company as soon as possible. If it needs to be stored, it should be stored in a dry, low temperature and dark place.
3. Collection methods and requirements of cigarette butts
1. Collect 2-3 cigarette butts that the appraiser has smoked (after removing the ash);
2. After collection, put the cigarette butts into a paper envelope (do not use plastic bags to seal), and make a mark.
Precautions:
1. Make sure that the collected cigarette butts have been smoked by the same appraiser;
2. Try to avoid touching the part of the cigarette butt smoked when collecting the sample; 3. Please send (mail) the sample to the identification center as soon as possible after the sample extraction is completed, so as to avoid DNA degradation due to environmental factors and affect the test results.
Fourth, amniotic fluid sample extraction
Special reminder! Amniotic fluid samples must be taken to a regular Grade 3 or above hospital, and extracted with the advice and help of a registered obstetrician and gynecologist with rich experience. To ensure the safety of pregnant women and fetuses. How much you can take during pregnancy depends on your doctor's diagnosis of your physical condition. The fetal amniotic fluid paternity test generally requires a 3-6 ml amniotic fluid sample. Samples must be identified as soon as possible, especially in summer when it is best to be delivered in an ice pack.
5. Oral sampling
Collecting DNA is very simple, painless, safe, hygienic, and can be done in one minute.
Note: Avoid touching the oral swab with your hands. All testers should rinse their mouths with water first. When the child is drinking milk, please take oral sampling after 1 hour; cotton swabs), clean envelopes.
1. First mark the clean paper envelope, mark the date of sample collection, sample identity such as: father, mother, child, etc., and name or code.
2. Put a cotton swab into the child's mouth, and gently scrape the two sides of the mouth (inner cheeks and cheeks) and under the tongue with the cotton swab, and then gently rotate or scrape it about 10 times before taking it out. Repeat 3- 5 will do.
Note: During the collection process, please do not touch the cotton ball part of the oral cotton swab with your hands, please rotate and brush with a little force to ensure enough DNA is obtained.
After the collection is completed, it can be directly packaged in a breathable paper envelope (the breathable envelope will dry naturally in the shade). (Do not use plastic bags because airtightness will cause the samples to become moldy or smelly, degrade DNA, and affect the experiment. Unless some special samples need to be stored in the refrigerator, the daily samples can be packaged in air-permeable envelopes.)
Note: Please do not mistake the sample, please make sure the sample is the same as the person marked on the packaging envelope.
Notes on oral swab samples:
Avoid touching the tip of the cotton swab with your hands, and rinse your mouth with water before collecting. The samples collected by the above method can be stored in a dry environment for 2-3 months.
Oral swabs need to be dried in the shade and put into paper envelopes to prevent mildew of the oral swabs from affecting the detection; oral swabs of different people need to be stored separately and identified.
Advantages of oral swab sample collection method: painless and convenient.
6. Hair collection
Precautions:
Avoid touching the hair follicles of the sample with your hands!
Basic hygiene conditions:
Clean hands, clean envelopes. First mark the clean envelope, mark the date of sample collection, and the identity of the sample, such as: father, child's name. From the hair, eyelashes, armpit hair, etc., pluck at least 5 hairs (the ends of the hairs are clearly visible to the naked eye).
Note: Do not touch the hair follicles of the hair with your hands during the collection process, and make sure that the hair follicles can be clearly seen with the naked eye at the ends of the hair. Immediately place freshly plucked hairs in a marked envelope. The hair needs to be checked for clearly visible follicles.
Advantages of the method of collecting hair samples:
Not limited by time and place, it is the easiest sampling method and has high concealment. The accuracy of using hair for paternity testing is exactly the same as that of sampling methods such as blood collection.
Note: Please do not touch the follicle part of the hair with your hands. Please do not load samples that have fallen on the ground and unplug samples that have been around for a long time. Please do not mistake the sample, please make sure that the sample matches the identity of the person marked on the plastic bag.
Identification method
1. Blood type identification. Blood type identification is the determination of biological relationship based on the genetic law of blood type. ABO blood type inheritance is controlled by three alleles A, B and O. Everyone has any two of these genes, and the two genes can be the same. When two chromosomes are paired, 6 kinds of genes can be combined, namely AA, AO, BB, BO, AB, OO. These 6 kinds of genes are the genetic basis that determines the individual characteristics of organisms, which are called genotypes. In contrast to this, the actual manifestation of human traits is called phenotype, which is commonly referred to as blood type. The paternity relationship is determined according to the inheritance law of blood type. All blood group systems are passed from parent to offspring according to Mendelian inheritance, and can be used as the basis for paternity testing.
2. The comparison of appearance characteristics in physiognomy, that is, according to the similarity of special features such as face shape, stature, ears, nose, eyes, etc., as an aid and reference for blood type testing. In addition, there are methods of examining skin texture, genetic diseases, earwax, taste blindness, inferring conception, childbirth, and determining reproductive capacity. The paternity test must comprehensively use the above methods, among which the blood type test is the main method. The development of modern biotechnology can also obtain DNA fingerprints by hybridizing the daughters of DNA fragments. This technology can be applied to paternity testing, which can reduce the random identity rate to one in 30 billion. The paternity test can generally draw three conclusions: deny paternity, affirm paternity, or neither affirm nor deny paternity.
Today's science and technology have greatly improved the accuracy of paternity testing. After using DNA gene identification technology, the accuracy rate of affirming biological father-son relationship is over 99.99%, and the accuracy of denying biological paternity relationship is 100% excluded. With the advancement of technology, the samples examined have been expanded from simple blood in the past to hair, saliva, bones, body fluids, etc. for identification, and even unborn fetuses can be identified using the amniotic fluid of pregnant women.
blood type inheritance
Special Note: The relationship between blood type and heredity is generally the same throughout life. Humans have four blood types, A, B, O, and AB. Blood types are inherited by means of chromosomes in cells. There are 23 pairs of chromosomes in human cells, and each pair consists of two single chromosomes, one from the father and one from the mother. The main component of chromosomes is deoxyribonucleic acid, which is often referred to as DNA, which determines hereditary traits and functions. DNA can be divided into many small segments, each of which has a specific genetic trait and function. These segments are called genes. Small pieces of DNA at the same location on two single chromosomes in a pair of chromosomes are called alleles.
The gene locus for the ABO blood group system is on chromosome 9. Human ABO blood type is controlled by three genes A, B and O, but there are only two ABO system genes on the ninth pair of chromosomes in each human cell, namely AO, AA, BO, BB, AB, OO. A pair of alleles, in which the A and B genes are dominant and the O gene is recessive. The inheritance law of ABO blood group system can be of reference value when the gene is not mutated, but blood type cannot be used alone to determine the blood relationship.
Strictly speaking, the blood group locus is only one of many genetic loci, which certainly has a certain reference value. However, because the routine blood type identification is known by naked eye observation under relatively simple conditions, there is a large error in it. Moreover, the blood type only represents one locus, and the DNA paternity test often has dozens or dozens of loci. In comparison, it appears to be less rigorous.
The principle of ABO blood group identification is to divide blood groups into four types: A, B, AB and O according to the presence or absence of A antigen or/and B antigen on red blood cells. ABO blood type can be accurately identified by positive (serum test) and negative (cell test) typing using hemagglutination test. The so-called positive typing is to use known anti-A and anti-B typing serum to determine whether there is corresponding A antigen or/and B antigen on red blood cells, and the so-called reverse typing is to use known A cells and B cells to determine whether there are corresponding A or B cells in the serum. of anti-A or anti-B.
Parent: A type + A type, offspring possible: A type, O type, offspring impossible: B type, AB type
Parent: B type + A type, offspring possible: A type, B type, AB type, O type, offspring impossible: none
Parent: B type + B type, offspring possible: B type, O type, offspring impossible: A type, AB type
Parent: one or both of them are AB type, offspring possible: A type, B type, AB type, offspring impossible: O type
Parent: A type + O type, offspring possible: A type, O type, offspring impossible: B type, AB type
Parent: B type + O type, offspring possible: B type, O type, offspring impossible: A type, AB type
Parent: O type + O type, offspring possible: O type (no variation, 100% O type), offspring impossible: A type, B type, AB type
Note: Blood type testing cannot be used as the standard for kinship. only DNA paternity testing is the gold standard for determining kinship.
Identify common sense
What is the difference between a forensic identification and a personal identification?
The identification methods and identification accuracy rates of legal and private identification are exactly the same. The only difference is that legal identification requires the subject to provide fingerprints, photos, and identification, and the sample sampling process needs to be carried out in the presence of legal witnesses. There is no need to provide photos or fingerprints for private identification, and the entire sampling process can be carried out by itself and is completely confidential. Therefore, the DNA identification results of privately collected specimens have no legal effect.
Can a paternity test be performed without the participation of the biological mother?
The biological mother may choose not to participate in the identification. In a paternity test, specimens from the child and the putative father are usually sufficient to know the results, and the mother may choose not to participate in the test. The biological mother is also tested, and the conclusion is more accurate. Because a child's genes come from the mother and the father. If there is a biological mother for reference (i.e., parental identification), you can more clearly deduce the biological father's genes based on the genotypes of the mother and the child, so as to compare with the disputed father (i.e. you). If there is no mother, the father's gene is directly deduced from the child's gene. There are many possible situations, and the numerical deviation obtained by the final statistics is relatively large.
In fact, the results of our commonly used detection of 15 STR loci have been performed in a computer simulation of a single parent case, two unrelated people, using this detection system, at least 3 violations of genetic laws, 99.99% of non-fathers It can be ruled out, but there is a 1/1000 possibility that it cannot be ruled out and it is wrongly identified. Therefore, the difference between our single parent identification and other institutions is that we also add a kit and 9 detection indicators, which are more accurate and avoid deviations as much as possible. This is also the reason why the single-parent identification fee is higher than that of the biological mother participating in the identification.
Do I need to be present for a paternity test?
The paternity test can be divided into two types, one is that it needs to have judicial effect, such as litigation, immigration, household registration, etc.; the other is just wanting to know the result and does not involve judicial purposes. For the former, it is enough to provide the identity documents of the parties, parents provide ID cards, and children can provide birth certificates or household registration books to prove their identity (proving that the principal is the guardian of the children). If you have entered judicial proceedings or have hired a lawyer, you can be commissioned by a judge or lawyer for identification. It can also be entrusted by both parties jointly or unilaterally. For the second type, you don't need to provide any information, you can be anonymous and you can bring your own samples. The fees, appraisal methods, and appraisal standards of the two types are exactly the same. The only difference is in the procedure, that is, the legally valid judicial appraisal certificate requires us to review the party's ID card and take a photo.
When is an immigration paternity test required?
1. One of the parents of the child is a non-Chinese nationality, the child was born in China, and the household registration relationship needs to be transferred abroad.
2. Both parents of the child are of non-Chinese nationality, the child was born in China, and the child settles abroad with the parents.
3. Foreign nationals who still have immediate family members in China who need to settle abroad;
4. The Chinese nationals have settled abroad, their children have moved with them, and other situations;
Fetal identification
Fetal paternity testing refers to the use of genetic technology to identify the father in the genetic sense of the fetus. When the genetic father of the fetus is unknown, the "prenatal paternity test" can extract cells from the amniotic fluid of the pregnant woman and confirm the father-son relationship by identifying the fetal DNA (deoxyribonucleic acid). A paternity test can detect fetal DNA from the time of the fetus through villus biopsy and amniotic fluid testing. After 10 weeks of pregnancy, you can do a chorionic puncture test, and after 16 weeks of pregnancy, you can do an amniotic fluid test. This article introduces the method of fetal paternity test.
1. Villus biopsy
1. The cleanliness of leucorrhea of pregnant women is required to be high, which is 1 degree;
2. Pregnant women should not have a cold, sore throat, fever and other inflammations
3. Routine blood test, low white blood cells
2. Amniotic fluid identification
1. Pregnant women should not have a cold, sore throat, fever and other inflammations
2. Routine blood test, low white blood cells
Pregnant and fetal identification tips:
1. Pregnant women need to pay attention to rest before surgery. If they have a cold, sore throat and fever, they cannot undergo surgery.
2. You can have breakfast on the day of the hospital examination, no need to take blood on an empty stomach
3. Pregnant women with villus biopsy need to do a b-ultrasound before coming. Determine the pregnancy period, do a leucorrhea examination, and the cleanliness is normal before surgery.
4. Pregnant women are not allowed to take a bath on the day after the operation, and they are not allowed to have sex for half a month.
5. Wear more clothes when going out to avoid catching a cold.
It is understood that the paternity test is divided into single-parent test and double-parent test, and most of them are single-parent test, that is, one spouse takes the child for the test without knowing the other, and the child always falsely calls "physical examination". According to the person in charge of the Judicial Appraisal Institute, more than 70% of the paternity testers are male. They all suspect that their partners are unfaithful and secretly bring their children to do the test in order to understand. "The child doesn't look like me" and "the child was born at the wrong time" are all reasons why these men suspect that the child is not his own. On the one hand, the rapid increase in the number of paternity tests shows that society is progressing, and people are willing to solve problems through scientific means. On the other hand, it also shows that there is a growing lack of trust and understanding among couples and lovers. The editor recommends that you must be cautious about the paternity test and have enough psychological tolerance for the results to avoid harm to your spouse and children.
Will a fetal paternity test cause harm to the pregnant woman and the fetus?
The forensic doctor of the identification center said that there is no need to worry at all, because this technology is very mature, whether it is taking villus or amniotic fluid samples, it is the same as the prenatal diagnosis of the fetus, and basically it will not cause any harm. The fetal paternity test is performed by extracting the villi or amniotic fluid from pregnant women. To ensure safety, it is recommended that pregnant women choose a top-three obstetrics and gynecology hospital for extraction. At present, the relevant technologies of the top three obstetrics and gynecology hospitals are mature and will not harm the fetus and pregnant women. The identification center has a special car to pick up the fetus and the staff to accompany the customer to take sampling services in the fetal paternity test. And the identification center has accepted tens of thousands of entrusted cases of fetal (prenatal) identification nationwide, and has rich identification experience.
face the result correctly
When we are going to do a paternity test, our mental state is the most important at this time. In the eyes of most people, the most direct and intuitive paternity test is to test whether the spouse (or wife, to be exact) is faithful. Men are not afraid of hardship, fatigue or even bloodshed. However, wearing a "green hat" is the most taboo and shameful thing for men...
The husband suspects that his wife has a "third party", and even coaxes and deceives the child to take the child for a "check-up" secretly, but he does a paternity test behind the scenes; the young girl deliberately "accidentally" gets pregnant in order to get rich. And using the paternity test as a threat, I am especially willing to be a "second wife"... I don't know when it started, the paternity test seems to have become a "patent" for digging "third parties" and "sugar daddy".
"Actually, this is a misunderstanding. The paternity test has extraordinary social significance in terms of finding relatives and corpses in disasters (such as earthquakes), finding abducted children, and helping raped women find evidence of suspects." To find evidence, raped women must wait until the child is born. This is undoubtedly an unbearable pain for the victimized women. Now, through fetal DNA identification, the biological "father" can be found.
As a forensic identification, paternity test is used to provide objective, scientific and neutral material evidence. The emergence of paternity testing technology should be a social progress. As a brand-new scientific method, it is actually paternity testing. Its original purpose is to reflect the right to know, so as to solve the crisis of trust in the family and resolve conflicts. An emotionally loyal "killer". The reason why paternity testing has become a sensitive social topic is that it involves the issue of men "wearing cuckolds". Using the method of paternity testing, modern people can easily determine the blood relationship between relatives. However, this "convenience" also brings more tests to the marriage relationship of modern people. I have called myself "Dad" for many years, and suddenly told myself very seriously: "I am not your father, because you are not my biological child..." The family was living a very harmonious life, but suddenly there was a report that they were not at all at all. It is not a "family", and the family's life will change from now on.
On the other hand, DNA paternity testing is becoming more and more popular, and is more and more known and accepted by most people. Many people choose to verify directly through technical means instead of tangled in their hearts. This should be regarded as a kind of The progress of society; in modern society, everyone's survival, life, and work are under great pressure. If a simple and direct method can be used to confirm or relieve the doubts in the heart, it is better than depression. There were not so many people doing the test before, but it was initially due to the immaturity of the technology and the limitation of the application field. For example, the original DNA paternity test technology could only be used for criminal cases and not for civil paternity test, and the test at that time The cost is high and the technical requirements are very high; fathers who have doubts about the parent-child relationship have no way to confirm their doubts.
China is a country that values blood ties and blood inheritance. The question of whether a father is his own child will be confirmed by scientific means and will continue forever. Procedures required for the immigrant paternity test: 1. When applying for the immigrant paternity test, the person to be authenticated needs to provide documents that can prove their identity (such as ID card, household registration book, birth certificate, etc., only one kind is required); 2. Some countries require the entrustment of a notary office when applying for a visa. If required, please provide the notary office with a power of attorney identification; immigration paternity identification process: 1. The appraiser signs a forensic identification power of attorney and collects samples at the identification center. You can also collect samples and mail them by yourself at the site of the identification center. 2. The collected samples will be sent to the laboratory for DNA testing, and the identified person can wait for the identification report. 3. The appraisal center will generally issue an appraisal report within 5 working days. It is recommended that the appraiser communicate with the customer service staff of the appraisal center in advance when doing the immigration paternity test. The customer service staff will help the appraiser with professional knowledge in the first time with the doubts and problems encountered in the appraisal process.
kinship identification
Genetic theory has confirmed that half of each child's genomic DNA comes from one parent. At present, the kinship identification carried out by the forensic material evidence profession includes the following categories:
1. Conventional biological blood relationship identification: This is the most in-demand type of paternity relationship identification, including parent-child tripartite (also known as triplet), father-son (or mother-son) both (also known as doublet) Paternity test. The accuracy of such identification can reach 99.999999%.
2. Intergenerational kinship identification: This type of identification refers to confirming the kinship between great-grandparents, grandparents, and great-grandchildren (great-granddaughters) and grandchildren (granddaughters). It also includes simple paternal kinship identification, such as to confirm the kinship between great-grandfather, grandfather, and great-grandson, grandson, and pure maternal kinship identification, such as to confirm the kinship between great-grandmother, grandmother, granddaughter, and great-granddaughter. .
3. Difficult kinship identification: In addition to the above two categories, there are some more difficult kinship identifications, such as the identification of compatriots (brothers, siblings, siblings, sisters) and cousins whose parents are suspected (no), Identification of kinship between uncles and nephews, between aunts and nieces, and between uncles and nephews (nieces).
