Understanding the Paternity Report

DNA paternity test result is one single way of determining paternity in a conclusive way. Results leave no loopholes and will either exclude or include an individual as the biological father of a child. You will need to be aware of three key terms which will be explained hereunder. These terms are mandatory to understanding the results to your paternity DNA test.

Key term 1: genetic loci

DNA (Deoxyribonucleic acid) is an extremely long and entangled molecule. Scientists will only analyze specific locations on the molecule; these locations are referred to as loci, or a single locus. The analysis will locate 21 of these loci and map them on a table on your results sheet. These loci can vary in size and shape from person to person, variations which are referred to as alleles. The left column of your DNA test results will show all 21 loci involved in the test. In a paternity DNA test, two numbers will be displayed for each locus. We inherit half our genetic material for each parent and the two numbers shown for each locus point will signify an allele we inherited from each parent. If the alleles (loci with varying lengths) happen to be identical then only one number will be displayed. The analysts will then compare the loci numbers of the people involved in the test to determine whether they are related or not.

The following example should give you a clear idea:

In a paternity test, the child will display the following two alleles, let us say 12, 19. The mother has alleles 21 and 19. This means that the child has inherited the 19 allele from the mother. This also tells us that the other 21 allele must have been inherited from the father if he is the biological father of the child.

It should be noted that exclusion of paternity in a DNA test relies on at least 3 unmatched markers, sometimes 2.

Key term 2: combined paternity index (CPI)

For each of the 15 loci examined in a DNA paternity test, our analysts will calculate a paternity index. Once they have all 15 paternity indices they then merge these data and calculate what is known as the combined paternity index (CPI).

The combined paternity index helps to further calculate, statistically, how similar the alleged father’s genetic material is to another random person in the population of his same ethnic group and thus, how likely it is that he is the father rather than any other unrelated individual within the group.

The combined paternity index will determine whether the alleged father has played a role in the child’s conception and give an inclusion rate of 99.99% or higher. If the father can be excluded as the biological father, then the exclusion will be 100% certain.

You can read more and actually view a sanitized sample DNA test result by clicking here.

Key term 3: amelogenin gene

The amelogenin gene is one of the genes that determines gender and is found on both the X chromosome and the Y chromosome.  The DNA paternity test takes 21 genetic loci, but one of these loci is in fact the amelogenin gene which simply determines sex. The statistical analysis is thus really based on 20 loci rather than 21 loci.

The gene is tested for the following reason:

It acts as a way of ensuring that participants in the test have not, deliberately or not, placed the wrong swabs in envelopes, for examples placing the mother’s DNA sample in the envelope designated for the father’s sample.

Testing results using discreet samples

In cases where one chooses to use discrete samples, for example, hair or nails, it is important to bear in mind the varying success rates in DNA extraction.  Moreover, such samples may require strict sample collection procedures. Once the DNA is extracted the test is like any other DNA test and is equally accurate. We will inform you adequately on discreet samples so please contact us or explore our section on discrete samples should you have any queries.

Contact us on info@homednadirect.ie for more information about your DNA paternity test result.

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