Amelogenin and Paternity Testing

14 Aug 2017

DNA paternity testing is the most reliable method to scientifically ascertain whether an alleged father is the biological father of a child. The testing can determine whether genetic relationships really exist between relatives. The test involves testing the amelogenin sex gene with is hereunder explained.

In the case of paternity testing, the DNA of the alleged father, the child and often the mother are taken under analysis by the laboratory. The lab will take a total of 21 genetic markers on the DNA samples provided and compare the number of matching markers between the profiles of father and son in order to establish or exclude paternity. Out of the 21 markers tested is the sex-determining gene, known as the amelogenin gene. We can thus say that comparison is between 20 markers rather than 21. This gene is found on both the X and Y chromosome.

The Basic of Sex

Males have XY chromosomes whilst females have XX chromosomes. The Y-chromosomes contains far less genetic information than the more complex X-chromosome.  Maleness is encoded in the Y-chromosome which is only passed on from father to son.

The term ‘gender’ will be avoided in this article as it carries cultural associations such as the roles males and females play in society and does not scientifically tie in with the purpose of this article.

Why test the Amelogenin sex gene in Paternity DNA tests?

There are a number of valid reasons to test this gene.  The client may think testing this gene redundant as DNA samples provided are labeled. However, the following will give insight as to why this gene is tested for.

1. Amelogenin sex gene testing acts as a means of quality control to make sure that the correct samples are being analyzed. It sometimes happens that clients might inadvertently place the father’s samples in the mother’s envelope. The results could potentially be erroneous if the laboratory dies not identify this problem. Moreover, knowing that the laboratory tests for this gene might put people off trying to fake paternity test results by deliberately placing the swabs in the wrong envelopes or submitting someone else’s samples.

2. In forensic DNA testing, the amelogenin gene can provide enlightening information to experts when bodies have decomposed beyond recognition. In such cases, samples of DNA can be tested to establish whether the remains found are actually male or female remains.

Amelogenin and False Results

In very rare cases, after amplification of the amelogenin gene, male DNA results turn out to be female. In such cases, there is a deletion of the amelogenin sex gene on the Y chromosome; hence, samples are wrongly classified as female DNA samples. In such cases, other genetic markers which are specific to the Y chromosome can be tested to solve the problem. Also, such cases are as rare as 0.001% of cases and thus are it is extremely unlikely that your paternity DNA testing results will be affected.