Establishing the Limits of TrueAllele® Casework: A Validation Study

The limits of the expert system, TrueAllele® Casework (TA), were explored using challenging mock casework profiles that included 17 single-source and 18 two-, 15 three- and 7 four-person DNA mixtures. The sensitivity (ability to detect a minor contributor) of the TA analysis process was examined by challenging the system with mixture DNA samples that exhibited allelic and locus dropout and other stochastic effects. The specificity (ability to exclude nondonors) was rigorously tested by interrogating TA derived genotypes with 100 nondonor profiles. The accuracy with which TA estimated mixture weights of contributors to the two-person mixtures was examined. Finally, first-degree relatives of donors were used to assess the ability of the system to exclude close relatives. TA demonstrated great accuracy, sensitivity, and specificity. TA correctly assigned mixture weights and excluded nearly all first-degree relatives. This study demonstrates the analysis power of the TrueAllele® Casework system.