Grandparent Test Case Studies

Situations where AccuPlex DNA succeeded where a lesser test failed.


All tests were completed in our laboratory. Please take note of the label of the x-axis (e.g. Likelihood of Relationship) for an accurate portrayal of the given results.

Case Example #1


A grandmother and child are compared to determine if her son could be the father. After testing 16 markers it is found that there was only a 30.80% probability of relationship (69.20% unrelated). We report any probability less than 80% as inconclusive. In other words, you cannot draw a conclusion from the information when it is below 80%. Ideally, we’d like to have the probability as close to 100% as possible in either direction (related or unrelated).

We asked for the mother’s sample and tested with the 16 marker test. The results were also inconclusive with a probability of relationship at 43.88% (56.12% unrelated). After testing 41 markers, the probability of the grandmother being related dropped to 0.01%, meaning that she was 99.99% probable to be unrelated to the child.

Case Example #2


In another grandmother and child comparison with 16 markers, the results were found to be a probability of relationship of 27.09% (72.90% probable to be unrelated). The mother was unavailable for testing and we proceeded with the 41 marker test. We found the probability to be 99.70% in favor of a relationship with the child. This illustrates the power of additional markers and why our inconclusive level is set at 80%. The 16 marker test was simply not strong enough and, at times, produce misleading results.

Case Example #3


This grandmother and child DNA comparison with 16 markers produced a nearly equal probability of being related or unrelated at 48.85%. After testing 41 markers, the probability increased to 87.26% probability of relationship. Of course, we would like the percentage to be higher and asked for the mother’s sample to strengthen the case.

Case Example #4


In this case, the alleged grandfather, child and mother were tested. The probability of relationship at 16 markers was 57.56%, which is inconclusive. The probability increased to 99.99% after testing the three participants with the 41 marker test.