The Science behind your DNA Test Report
After samples have been received at the laboratories, the initial stages of DNA testing include the extraction, replication and analysis of your DNA from the swabs provided. The lab will analyze specific regions on the DNA profile with a total of 21 of these regions covered. We refer to these regions as genetic markers (genetic markers, sometimes called “loci”, are essentially DNA sequences with an exact location on our chromosomes). For each of these genetic markers (or loci) we have 2 alleles expressed in the test result – one allele is always inherited from our father and the other from our mother.
The way through which a parental match is found and thus, the alleged father confirmed as the biological father of the child is by comparing alleles on the profile of the alleged father and child to see whether these correspond. For example, if the child’s alleles marks 14 and 17 and the mother’s alleles mark 14 and 18 for a specific locus, we can see that there is a match on marker 14 – this allele was inherited by the child from his or her biological mother. We are now left with the child’s allele number 17 which we know was inherited from the paternal side (this can be deduced even without testing the father by simple process of elimination). The laboratory tests a total of 20 genetic markers which put together form the person’s DNA profile. All 20 markers must be shared between alleged father and child in order to confirm a paternal biological match – in other words, the alleged father and child must have matching alleles on all counts. If markers do not match, then the result will exclude the tested male as the biological father of the child. In all our paternity tests we encourage the mother to also provide DNA samples. Interested in reading more about our paternity testing services? Visit this page.
What does your Report Tell You?
Your report is provided to you on a single page, and displays a DNA profile for each person within the group who submitted their DNA samples. Our profile report gives you information about alleged paternal relationships and highlights the probability percentage of biological links. In the first column of your report you will see numbers that are indicative of the 15 loci mentioned above. The columns marked as ‘allele’ show the number of the alleles marked at each locus. Out of the total of 21 loci, 20 are used as genetic markers for the test and 1 is a locus that verifies the sex of the person taking the test.
The ‘Paternity Index’ in the report refers to a relationship index whereby calculations are made at each locus based on male populations that have fixed paternal allele at certain loci sites. The index highlights the readings found at each DNA locus site.
At the base of the chart you will find a ‘Combined Paternity Index’. This is a calculation of all the tested alleles taking each of the paternity indexes mentioned above, which in turn is used to conclude the probability of paternity.The degree to which the DNA of the alleged father is consistent with that of the child will yield results of whether the alleged father is excluded or not excluded from being the paternal father. “Excluded” means that the alleged father is not the biological father. Conversely, “not excluded” means that the probability of the alleged father and child sharing a paternal relationship is very high (99.99%).
A result cannot produce a 100% accuracy rate, as this would require testing the full DNA profile belonging to the individuals in question and no laboratory in the world does this. Our accuracy rates however boast an extremely reliable percentage of 99.99%.
More Important Terms
If you are interested in more important terminology and key terms associated with DNA testing, why not visit our glossary?