It is not necessary to wait until the baby is born to determine who the father is.
At Genolife we offer the NON INVASIVE PRENATAL test, which can be done from the 11th week of gestation.
A paternity test determines the biological lineage between a child and an alleged father and can be performed before or after the birth of the child. The common method of postnatal paternity is performed by analyzing genetic information obtained from buccal swabs or some other biological sample from the child or alleged father to generate a probability of paternity. (2)
The main challenge in implementing a prenatal paternity test lies in obtaining fetal DNA. The methods of obtaining this DNA can be divided into invasive and non-invasive. Invasive samples include chorionic villus sampling or amniocentesis to obtain amniotic fluid; these obstetric procedures are no longer recommended because they can induce a high risk of miscarriage and infection, among other complications. Non-invasive sampling refers to the collection of whole blood from the mother in which fetal DNA is present as cell-free DNA (cfDNA), and since its discovery in 1997 a variety of cfDNA-based methods have been developed for numerous clinical applications. (1, 2)
Currently, non-invasive prenatal paternity testing is the most accurate, safest and earliest way to determine paternity before the baby is born, and requires the latest technology combining microarrays with single nucleotide polymorphisms (SNPs) and a paternity algorithm (2).
During pregnancy, the baby's DNA is naturally found in the mother's whole blood and is increasing from the first trimester onwards from 3 -13% of the total free circulating DNA in maternal plasma. A very low amount of circulating fetal DNA is a crucial problem, requiring specific techniques to optimize and purify it from maternal plasma, in conjunction with highly sensitive detection by next-generation sequencing (NGS) technology (1).
The test requires a whole blood sample from the mother with at least 11 SDG (approx. 20 ml), then a process of extraction and isolation of circulating nucleic acids from the baby's DNA is performed and compared with the DNA taken from the possible father by buccal swabbing. The probability of paternity is determined by an initial analysis of a panel of 356 SNP's and expanded to 2,304 SNP's (2).
In a conventional postnatal paternity test, autosomal genetic markers (STRs) are used and 15 to 20 are required to generate highly accurate results, with the standard for paternity probability of inclusion set at 99.9999%. In contrast, with noninvasive prenatal paternity testing SNP-based approaches are superior, requiring 108 to 174 SNP's classified as effective to calculate a paternity probability of inclusion >99.999999 by performing systematic selection based on population genetic information and selection criteria that simplify calculations, reduce SNP redundancy, and increase discriminatory power.(2)
The algorithm used uses a formula that incorporates the test results and produces a confidence level in the probability, which is equivalent to the combined paternity index. The probability of paternity is generated by comparison with unrelated individuals in the general population and a neutral database is used, so it is not required to know the race of the alleged father or mother in order to perform the calculation.
For most women, fetal DNA levels increase throughout their pregnancy. However, there is a small percentage of women who do not have sufficient fetal DNA in their bloodstream (even in the last months of their pregnancy) due to various factors such as their metabolism or immune system activity directly affecting circulating DNA, and are NOT candidates for this test.
When the amount of fetal DNA or that of the presumed father is not sufficient for the analysis, a new sample will be requested, increasing the time for the delivery of results but not the cost, with the probability that it is a case like the one mentioned in point number 1.
More than one alleged father can be added to this test, but must be requested (at extra cost) at the time of the first sample taken, once the analysis has begun it will no longer be possible to include them and you will have to start again.
This test is not intended for use in closely related parents, incest, surrogate pregnancies, donor eggs, in vitro fertilization or twin pregnancies.
5.- This test can also not be performed in people who have had bone marrow transplants, blood transfusions, immune therapy or stem cell therapy because it is possible that there may be interference in the result by contamination of other external DNA.
Paternity Test: Non-invasive Prenatal
- Digital and in-app reporting
- Appointment with an interpreter