The importance of including maternal profiles in paternity testing – three cases of possible false inclusion with duo-only testing

Abstract

There are frequent requests for duo paternity tests thus increasing the possibility of false paternity inclusions. The aim of this study was to identify possible false inclusions when comparing the duo to the trio paternity profile to see if there is a discrepancy in the results when using 15-loci autosomal short tandem repeat (STR) analysis. We concluded that wrongful inclusions would have occurred in duo paternity profiles in three cases out of 240 trio exclusions. Paternity probabilities between 95.0688215064% and 99.99964871% were calculated on the duos. We demonstrated how duo results were changed from an inclusion to a definite exclusion when the mother’s DNA profile was added to the test, showing the importance of the mother’s profile in paternity testing and the risk of false inclusions in duo cases. These findings support the literature where false inclusions are reported in a paternity test where the mother’s profile is omitted, as well as the recommendation for 3 or more mismatches as an exclusion criterion