Análisis de paternidad - LGS Análisis

What is the paternity test?

The test for the biological investigation of paternity is the test whose objective is to assign or exclude the paternal-filial genetic link. This test. which is conducted by the comparative analysis of DNA polymorphisms of both to determine or exclude genetic relationship, is maximally reliable.

The samples for the paternity test

The epithelial cells of the oral mucous membrane are currently the sample of choice, due to the fact that it is easily obtained, because it is non-invasive, is easily conserved and gives excellent results. It is obtained by rubbing the internal part of the cheek with dry sterile-cotton swabs. Two swabs are taken, one on the inside of the right cheek and one on the inside of the left.

Although this is the most usual way of obtaining the biological material for the test, the DNA can also be obtained by the extraction of blood, from drinking glasses, stamps, bloodstains or sweat, nail cuttings, toothbrushes, children’s dummies, chewing gum, milk teeth or hair that has been pulled out including the root, for example.

The two types of paternity test

Paternity tests may be of two types, according to the purpose. On the one hand, there are paternity tests with legal validity, that is to say, those which are carried out when the applicant needs an expert report in which both the result of the paternity and the names of all the persons involved are given. These reports are used in registries and courts of law.

On the other hand, we have informative paternity tests. They are carried out at the request of a private person who is interested in confirming or excluding paternity. This kind of test does not have validity in law and in the final report the names of the persons involved do not appear. Furthermore, the applicant must bring the samples to the laboratory.

  1. 1
    How many days will I have to wait for the result of the paternity test?

    The result of the tests will be available twenty days after receiving the samples.

  2. 2
    Can the paternity test be carried out before a baby is born?

    Yes, it can be carried out on samples of amniotic fluid and on samples of chorionic villi, so the patient would have to go to her gynaecologist.

  3. 3
    Can the paternity test by carried out at home?

    At LGS Análisis, we carry out these tests at home when there is a person who has mobility problems or when a judge or an official organisation so requests.

  4. 4
    Is the result confidential?

    In tests requested anonymously, the laboratory does not take part in the taking of samples; the applicant will sign a document accepting the conditions and the result will be totally confidential . Only a closed report is given to the applicant. In the report, there are no names of any of the samples involved.

    If the tests are requested for legal reasons, they must be carried out following the protocol established for these cases. Furthermore, the parties must come in person to the extraction centre.

  5. 5
    How is the comparative analysis of the two samples carried out?

    Only 10% of nuclear DNA codifies what we are and what we are like. Of that 10%, human beings share nearly everything. So, if what we want is something that will serve to tell certain people apart from others, the codifying DNA, in general terms and although it has its polymorphisms, will serve little purpose.

    On the other hand, within the non-codifying DNA there are areas of extraordinary variability between one person and another, which we call “polymorphisms”. Also, as a result of the use we make of it, they are called DNA markers.

    From the described biological samples, the DNA is extracted by means of the organic extraction method of formaldehyde/chloroform, then the DNA is purified and by means of a polymerase chain reaction technique a total of sixteen genetic markers validated by STADNAP (Standard of DNA profile techniques of the European Union) and we recommend by the ISFG (International Society of Forensic Genetics). And the PCR products are analysed by means of the fragment analysis technique, using an automatic DNA sequencer.

  6. 6
    What degree of reliability do paternity tests have?

    With regard to the result of the tests, they may give a number of different details. They can determine that there is no relationship between the alleged father and the alleged son. Or, on the other hand, the tests of the sequences may show a complete genetic similarity, thereby confirming the paternity with maximal reliability.