In our laboratory, we routinely test 16 genetic markers that are known for being highly differential between individuals. A DNA paternity test compares the sizes of these markers between an alleged father and a child. Each DNA marker contains two alleles, one inherited from the biological mother and the other from the biological father. The DNA test finds out whether there is at least one match out of the two alleles on the same marker from the alleged parent’s and child’s DNA. The following table shows partial results of a paternity test. The numbers in blue indicate alleles that the child inherited from the alleged father.
|DNA Marker||Mother||Child||Alleged Father|
|D21S11||28, 30||28, 31||29, 31|
|D7S820||9, 10||10, 11||11, 12|
|TH01||14, 15||14, 16||15, 16|
|D13S317||7, 8||7, 9||8, 9|
|D19S433||14, 16.2||14, 15||15, 17|
The partial results indicate that the child and the alleged father’s DNA match among these five markers. The complete test results show this correlation on 16 markers between the child and the tested man to draw a conclusion of whether or not the man is the biological father.
Scientifically, each marker is assigned with a Paternity Index (PI), which is a statistical measure of how powerfully a match at a particular marker indicates paternity. The PI of each marker is multiplied with each other to generate the Combined Paternity Index (CPI), which indicates the overall probability of an individual being the biological father of the tested child relative to any random man from the entire population of the same race. The CPI is then converted into a Probability of Paternity showing the degree of relatedness between the alleged father and child.
Our laboratory always achieves a 0% probability of paternity if the tested man is not the biological father and at least 99.9% probability of paternity if the tested man is the biological father. Both results are conclusive to prove or disprove paternity.
The chain-of-custody testing results issued by our laboratory include the following information:
- All tested parties’ names as shown on their IDs presented at specimen collection
- Listing of each tested party’s individual DNA profile
- A Combined Paternity Index
- A Probability of Paternity
- A statement of conclusion
- Copy of chain-of-custody documents including clients’ IDs, consent forms, and photos.
Every report is signed out by our M.D. laboratory director.
In other family relationship DNA tests, all tested parties’ genetic profiles are generated and compared to see the probability of relatedness.
If you have any questions about your DNA testing results, please call our knowledgeable case managers at 1-800-914-1002. They will be happy to explain the results to you.