Paternity DNA Tests and the Analysis of the Amelogenin Gene

12 Aug 2017

Paternity DNA Testing is the only scientifically grounded method that can establish whether an alleged father is the true father to a child. DNA testing is sound and extremely reliable and the number of tests available keeps growing as scientists learn more and more about our genes and how so many factors relating to us as humans are intrinsically tied to those genes. Our genes we inherit from our parents and amongst these is the amelogenin sex gene.

The Accuracy of a DNA Paternity Test

A DNA paternity test relies on very sophisticated laboratory equipment and highly skilled scientists to locate what are known as genetic markers. The DNA molecule is extremely long and convoluted. The better laboratories locate a total of 24 genetic markers on the alleged father’s DNA and that of the child. They then see if the markers between father and child are identical so as to determine whether the father can be excluded or included as the paternal father; it the markers all match, then tested father is the child’s biological father. They will then issue a statistical probability that will state that the alleged father is the biological father of the child with a 99.99% probability and exclude the father with a 100% probability. Learn how to understand paternity test results.

The Amelogenin Sex Gene

The total marker’s taken under examination are 24; however, one of these genetic markers is the amelogenin sex gene and is one of the more important genes which determines whether someone is male or female. Females have 23 XX chromosome pairs and males have 23 XY chromosome pairs. The amelogenin gene is found on the X and the Y chromosome, although there can be some anomalies in these gene in certain individuals which will be discussed later in the article.

The Importance of Testing this Sex Gene

The testing of this gene is done under three main circumstances. This first reason is as a means of quality control in a DNA Paternity test as clients tend to sometimes misplace mouth swabs and put the father’s swabs into the mother’s envelope. This misplacement can be done on purpose or by mistake; whichever the case, testing for the amelogenin gene will confirm whether the DNA samples being analyzed belong to a male or a female.  The second reason happens in forensic  testing, for example in cases where a crime has been committed and a corpse does not allow immediate identification due to excessive decomposition, then forensic experts will test of the amelogenin  gene to conclude whether the remains belong to a male or a female. Finally, in cases where a person chooses to do an infidelity test and sends in some suspect DNA, analysts will test for the amelogenin gene to see if the suspect DNA found in the stain belongs to a male or a female.

Anomalies when Testing the Sex Gene

As stated, the amelogenin gene is found on both the X chromosome and the Y chromosome. The differences in the size of the amelogenin gene on the X and Y chromosome have been used to determine gender in DNA testing. In some cases, around 0.001%, a deletion occurs on the Y-specific amelogenin gene; in such cases, males samples will erroneously result as female sample. If this happens, laboratories will analyze additional markers on the Y chromosome so as to have clear gender identification.  The incidence rate of this is so low that people thinking of doing a paternity DNA test need not even consider it.