The Amelogenin Sex Gene in a Paternity DNA Test
Anyone wishing to know who the biological father of a child is will likely opt for a paternity DNA test; this is the only reliable means that can fully determine such issues with outstanding accuracy. DNA testing rarely leaves questions unanswered and the number of tests available keeps growing as scientists learn more and more about our genetic makeup. To fully understand you test your should be aware of what amelogenin is.
In a DNA paternity test, scientists will take an optimal number of 21 genetic markers on a DNA sample. They will examine very specific locations on the long and entangled DNA molecule and create a genetic profile for the alleged father and child. They then go on to see how many of the genetic markers identified correspond between father and child. The true biological father of the child will have all 15 of these markers match with those of the child.
Why are only 20 Markers Compared when there a Total of 21 Markers Tested?
If any less than 20 markers match between an alleged father and child in a DNA paternity than the individual is excluded as the child’s biological father. The 21th genetic marker tested is known as the amelogenin gene and simply determines the sex of the child. However, it is standard procedure to test this gene in a DNA test. Females have a pair of XX chromosomes and males have a pair of XY chromosomes; the sex gene is found on both the chromosomes.
Testing the Amelogenin Sex Gene is Important in Paternity DNA testing because:
- It acts as a quality control measure which is crucial for the reliability and accuracy of results. Such control as done by testing this gene ensures that the correct samples are being analyzed. Sometimes, clients may place the mother’s samples in the envelope allocated to the father’s samples or vice versa; in such cases, any laboratory concluding the test without noticing the mistake would generate wrong results.
- In cases where there is extensive decomposition of human remains that need to be identified, forensic teams will test for the amelogenin gene to see if the remains found belong to a male or female.
- In cases where an infidelity DNA test is carried out, the suspect stains provided by the client will be tested for the amelogenin sex gene to determine whether the stains are male or female. Moreover, if there are DNA samples of both a male and female mixed together, testing for this gene will identify these two sexes.
Problems when Testing the Sex Gene
As stated, amelogenin is found on both the Y chromosome and the X chromosome. In some instances, there is what is known as deletion of the gene on the Y chromosome and thus, the gene does not appear on this chromosome when analyzed. In such cases, male samples will appear to belong to a female. In such cases, laboratories will analyze some extra Y chromosome specific markers that will conclude the test. Such deletions of amelogenin are extremely rare phenomena and account for around 0.001% of all DNA tests. Given this low occurrence, this phenomenon should be of no concern o anyone considering a paternity DNA test.