Why Screen when You Can Y-Screen: Comparison of Serology and Y-Screening Methods Using the QIAGEN Investigator ® Casework GO! Kit

Conventional serological screening and processing of sexual assault evidence is time-consuming and labor-intensive. Direct-to-DNA male screening, or Y-screening, offers an alternative to these methods, minimizing sample consumption and introducing a more objective and meaningful screening metric. Despite the growing adoption of Y-screening in sexual assault evidence analysis, few published studies demonstrate its efficacy with case-relevant samples. This study bridges that gap by comprehensively examining semen dilutions on vaginal swabs and postcoital vaginal swabs. Two Y-screening methods (swab Y-screening and pellet Y-screening) utilizing the Investigator ® Casework GO! Kit were compared with conventional serological screening methods. The results demonstrate the effectiveness of these Y-screening methods in accurately predicting the presence of male DNA and its integration into a standard differential DNA extraction workflow. The novel pellet Y-screening method was assessed as the optimal method, displaying greater discrimination compared with acid phosphatase (AP) screening and increased sensitivity compared with prostate-specific antigen (p30) testing and microscopic examination with Christmas Tree staining. Modifications to the differential extraction workflow following pellet Y-screening improved the range of log likelihood ratios (LRs) of detecting male profiles in postcoital vaginal swabs (log LRs 17–25) compared with control direct-to-differential extraction profiles (log LRs 8–25). Additionally, both swab Y-screening and pellet Y-screening methods can be compatible with post hoc confirmatory microscopic examinations that laboratories may be required to perform. These findings demonstrate the suitability of Y-screening with the Investigator Casework GO! Kit as a superior alternative to traditional serological screening.