DNA typing and Parentage Testing
What is DNA Typing?
DNA typing is a method of identifying individuals from the differences in their DNA. It is also used to determine familial relationships between individuals.
Advantages of DNA Typing
The science of DNA typing relies on technology that allows an individual's DNA to be examined and analyzed. A person's DNA is unique: no two individuals (with the exception of identical twins) have the same DNA. Every cell in a person's body has the same DNA. Hence, DNA taken from any part of the body from the same individual will always be the same. DNA typing can be performed from many types of biological specimens including blood, saliva, sperm cells, muscle, teeth and bones. Thus, a person's DNA can be typed from very little tissue or body fluid. DNA typing is used for two major purposes: first, it is used to identify individuals from biological samples. This is mainly done in forensic casework, where it is possible to determine the identity of a criminal by typing the DNA left behind at the scene of the crime. The second important use of DNA typing is to determine familial relationships.
There are many situations where this kind of typing is needed, such as paternity testing, maternity testing, grand-parent testing, and even the identification of mutilated bodies is done by determining familial relationships. DNA typing is the best method of identifying individuals and determining familial relationships because it is extremely sensitive: that is, with even a very small amount of tissue, the test can be performed successfully. It is also very accurate: it can give a test result with a very high degree of certainty. Furthermore, it is very reliable because the chance of obtaining a false result can be minimized, and the chance of making an error in the conclusion can be calculated.
How does DNA Typing work?
In the DNA typing process, a DNA banding pattern or profile of an individual is first obtained from a tissue sample. The DNA profile is observed in the form of a set of DNA bands known as alleles. Each person has a maximum of two specific alleles for a given genetic location. This DNA profile is compared with the profile obtained from a sample taken from the scene of a crime. If the alleles in the two profiles match, then it can be said that the sample taken from the scene of the crime is from the individual that was tested.
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DNA typing services
Child custody and maintenance: in cases where one parent is claiming the custody and maintenance of a child and the other parent is refusing to accept parentage.
Proof of adultery: especially in divorce cases where the paternity of the child is suspect, and the wife is being accused of adultery, DNA typing can be used to determine whether the husband is the father of the child.
Rape, which has resulted in pregnancy: DNA typing of tissue samples from the mother, child and suspected offender can be analyzed to determine whether he is the father of the child.
Testamentary cases: when a deceased person's wealth is to be distributed among his or her heirs, it is sometimes necessary to determine who the heirs are. DNA typing can be used to prove blood relationship to the deceased individual.
Immigration: Individuals and families interested in establishing a proven biological link to their relatives ultimately enhance their chances of a successful application for immigration. Identity testing in cases involving immigration may include answering questions of paternity, maternity, and sibling relationships.
Twin studies: DNA typing can be used to determine whether twins are identical or not.
Identification of mutilated bodies: when a deceased person's body is mutilated, and cannot be identified directly, such as in fire, vehicle accidents, bomb blasts,or due to prolonged burial, it is possible to identify these persons by comparing their DNA profiles with that of their close relatives'.
Murder, violent assault, robbery: in such cases, a sample of tissue from the criminal is sometimes found at the scene of the crime, and if there is a suspect, DNA typing can very accurately determine whether the sample of tissue belongs to the suspect, thereby linking the suspect to the crime. Furthermore, a sample of tissue from the victim may be found on the criminal (such as blood stains on the criminal's clothing). Similarly, DNA typing can be used determine whether the sample of tissue belongs to the victim in such cases, thereby connecting the suspect to the victim.
Rape and other sexual offences: in these cases, semen and saliva samples may be obtained from the body and clothing of the victim. DNA typing can be used to determine whether the sample of tissue belongs to the suspect, thereby linking the suspect to the crime. In such cases, DNA typing can be used very effectively to identify the criminal only if the offense is reported immediately, and DNA samples are taken as soon as possible.
Establishment of identity in insurance claims: It is often necessary to establish the identity of a claimant in life insurance claims. DNA typing can determine the relationship of the claimant to the insured individual. DNA typing is also extremely effective in identifying individuals who have died in accidents or by other causes, and whose bodies have been severely mutilated making conventional identification impossible. Hence, DNA typing can be used to confirm the death of the insured person.
Establishment of a criminal DNA profile data bank: Many countries have enacted legislation to establish a DNA databank, containing profiles from individuals convicted of specific crimes, especially violent crimes and sexual offences. Law enforcement agencies search these databanks for matches with DNA profiles from biological evidence of unsolved crimes. Using these databanks, law enforcement agencies have been successful in identifying suspects in cases thought to be unsolvable. Such databases are also a powerful deterrent to crime, because the criminal knows that his DNA profile is on record.
DNA typing is a highly specialized procedure which requires knowledge and skill. Furthermore, for DNA typing evidence to be acceptable in a Court of Law, it has to meet certain quality standards, which have been well documented and followed by forensic DNA laboratories worldwide. The most accepted of these standards are those set by the Federal Bureau of Investigation (FBI), USA, the International Society of Forensic Genetics (ISFG) and Scientific Working Group on DNA Analysis Method (SWGDAM). The American Association of Blood Banks is also an important provider of standards for paternity testing casework. We at Genetech are proud to announce that every step of our DNA typing process meets with these international standards.
At Genetech, our quality standards cover all aspects of DNA typing, including qualified and experienced personnel, the latest equipment, and the best of chemicals and reagents. The entire process is performed to generate error-free results which can be verified by any laboratory anywhere in the world.
Personnel: Genetech has the most experienced and qualified personnel in the field of DNA typing in Sri Lanka. They have pioneered DNA typing in this country, and have laid the groundwork for the application of this technology in Sri Lanka.
Equipment: Genetech is a fully equipped facility, which has the ability to perform procedures in molecular haemogenetics in the exact manner required by the standards. The equipment at Genetech is regularly calibrated to ensure error-free functioning.
Laboratory management: All aspects of laboratory management and documentation are performed to meet with the standards. Aspects of confidentiality, security and independence have been diligently maintained.
Technical quality: The type of DNA testing done by Genetech is the latest, most accepted method known as Polymerase Chain Reaction (PCR) based analysis of Short Tandem Repeats (STRs). This method is presently accepted by the forensic community as the method of choice because of its sensitivity, accuracy, rapidity and cost effectiveness.
The type of genetic test: STR loci (genetic locations) which are tested by Genetech are those that are well studied and regularly used by the forensic community. Moreover, the STR loci tested by Genetech are among the most accepted, internationally. These STR loci have also been tested for their suitability to be used for the Sri Lankan population, and have been proven to be statistically suitable. There is also an established Sri Lankan population database for these loci, which enables such DNA evidence to be presented to a Court of Law.
Error minimization: In order to minimize the possibility of error, Genetech will maintain standards of validation and verification. The analysis of casework samples will be done alongside internationally used standard human DNA, and the results of the casework analysis will be subject to comparison with these DNA standards. Negative controls will be run at every step of the analysis procedure, in order to ensure that no cross-contamination of DNA has occurred.
Reporting: Once DNA typing results are generated, they are stored in both a graphic format as well as in a numerical format. An individual's DNA profile can be submitted to a Court of Law in both formats. Scientists at Genetech can provide statistical interpretation of the results, and express the accuracy of the test by statistical means, using data generated from the Sri Lankan human population databases. In order to be valid in a Court of Law, DNA evidence must be supported by statistical data. This data is obtained only by establishing a population database for the population group that is being tested. Therefore, only Sri Lankan population data can be used for such analyses.
Accuracy of evidence
DNA testing is the most accurate and reliable means of identity verification and parentage testing. The degree of accuracy of the test will depend on the genetic diversity of the Sri Lankan population, as well as the number of genetic locations (STR loci) which are tested. There is no mandatory number of STR loci required for a test, but the testing of nine STR loci or more is generally considered to be sufficiently accurate. Genetech tests up to 15 STR loci.
Accuracy in a test of familial relationships: A paternity or maternity test can prove with 100% certainty that an individual IS NOT the biological parent of a child.
No DNA test available can prove with 100% certainty that a man or woman IS the biological parent of a child. Generally, a degree of certainty of over 99% is required to accept the paternity or maternity of an individual. DNA testing by Genetech typically proves paternity with at least 99.9% certainty. This is well in excess of the required accuracy.
Accuracy in criminal casework: In criminal casework, the demand for accuracy is greater, and the forensic scientist has to prove beyond a doubt that a suspect's DNA profile matches with that of the criminal. This involves expressing the chance or probability of finding a random person in the population who might have this same profile. This probability or chance is known as the Match Probability. This probability must be very low. The lower the Match Probability, the greater the accuracy of the conclusions of the DNA test. There is no internationally agreed lower limit for this probability, but the result is generally accepted if it is lower than 1 in 1 billion. At Genetech, a sufficient number of loci can be tested to ensure that the Match Probability is lower than 1 in 10 billion.
DNA typing is performed ethically only with the informed consent of the individual whose DNA is being typed. The persons concerned will be informed about the consequences of the test. Where such consent cannot be given such as in the case of minors, the consent of the guardian has to be obtained. Genetech will not undertake samples for parentage testing without written consent from all living parties who will be tested.
In the instance of criminal casework, Genetech adheres to provisions in the Law, with respect to taking samples from suspects, victims and other living individuals involved in the case.
Strict confidentiality will be maintained at all times with respect to individuals being tested. The results of DNA typing tests and the conclusions drawn from them will be divulged only to the persons being tested, and Courts of Law which order such tests.
The test result will be given in a numerical format; a Scientist from Genetech will interpret the results, drawing a clear, unambiguous conclusion, and express it in simple terms.
DNA typing is performed by analyzing non-coding regions of an individual's DNA. It does not give the analyst any information about the ethnicity, race, social background, physical or mental make up of that person. Therefore, no other genetic information will be retrieved from an individual's DNA.
We are happy to announce that after much research and optimization, we have streamlined our DNA typing methods, and we are therefore able to provide DNA typing services at perhaps the lowest cost anywhere in the world. Genetech performs the same DNA typing tests which are used by internationally recognized laboratories, and maintains the same standards of quality, so that the conclusions made by Genetech can be verified by any accredited forensic DNA typing laboratory anywhere in the world. Please contact us for pricing.