The fastest and most accurate procedure commonly used to establish paternity is DNA testing. It allows paternity to be confirmed with a probability of 99.99% (in population genetics statistics it is referred to as "virtually inherited") or to be excluded with 100%. Such a high probability result is due to the use of the two most important characteristics of DNA molecules in the test (inherited DNA and DNA polymorphism).
Characteristics of the test
The test procedure involves collecting genetic material by swabbing (with a special stick from the inside of the cheek). The epidermal cells collected in this way, although invisible to the naked eye, have large amounts of DNA in them (1000 times the amount required for the test).
There are situations where the material is collected in a non-standard manner:
- a toothbrush is examined,
- plucked hair with the bulb.
Stages of examination:
- The swab stick (sample with genetic material), under sterile conditions and with extreme care, is immersed in a solution of an agent that dissolves fats and an enzyme that dissolves proteins. This is done in a special heating device (thermoblock). This action completely destroys the cells - all that remains is pure DNA floating in the resulting solution.
- The DNA solution is placed in a laboratory centrifuge. Its task is to separate the residual cells from the DNA, which settles on a special sieve and is washed away with another solution.
- The pure DNA is returned for the 'proper' analysis.
The subsequent laboratory procedures carried out produce a set of several dozen DNA fragments, the combination of which varies throughout the population. The resulting material is placed in a glass capillary (a tube with a diameter of 50 micrometres) filled with a special gel. A current is connected to both ends of the capillary, which causes the DNA to move from one end to the other. A laser and detector connected to a computer equipped with appropriate software detect the moving DNA.
The time it takes for a given DNA marker to pass through the tube, allows its unique length to be determined accurately, which is then compared in the test subjects.
The DNA markers in each person come in two variants - the child, in turn, inherits one of each from each parent. If one is present in the mother, the other must be present in the father.
When all the fragments tested match the DNA of the mother and the man being tested, then the probability of paternity is calculated (it must be 99.99% to be considered reliable). In a situation where the child has DNA markers not present in the mother and the alleged father - paternity is ruled out.
Important! In court paternity cases, only results from facilities certified by the Commission of Forensic Haemogenetics of the Polish Society of Forensic Medicine and Criminology are reliable.
The collection of genetic material takes place by an authorised person in the presence of the parents (a protocol must be drawn up). In alimony court cases, the tests are often performed without the participation of the mother.
The test can also be performed before the birth of the child - samples are either taken during prenatal testing or are isolated from the mother's blood.
Important! It does not matter for the certainty of the result whether the test is performed during pregnancy or after the birth of the child.
Cost of the test
The National Health Fund does not reimburse DNA paternity testing. However, the person requesting the test may be exempted from payment in the following situations:
- the child concerned is in an educational establishment,
- a difficult financial situation makes it impossible for either party to pay for the paternity test.
In the aforementioned cases, the costs for the genetic test conducted to confirm paternity shall be paid in full by the State Treasury.
