P664: Comparative evaluation of an AI-based scanner-agnostic add-on utility versus conventional karyotyping software

There were 29 unique ordering institutions, nearly all of which (93%) were formally affiliated with a medical school or university.The remaining 7% of institutions included a private pediatric hospital and a general acute care hospital.Sixty-six percent of institutions ordered URGS for >1 individual.The most common HPO terms in the cohort included seizure, respiratory failure, and hypoxemia, each of which was reported in at least 25 individuals.Overall, there were 819 unique HPO terms.The rationale for ordering URGS was provided in 42% of cases, with the most frequent themes including broad differential diagnosis, results required to inform management, and urgency of results required for a critically ill individual.URGS yielded positive results in 29% of individuals, possible findings in 34%, and negative results in 37%.Out of 52 individuals who received both a preliminary and final report, 74% (n=39) showed complete concordance between the results.In the 26% of individuals with a difference in the final and preliminary reports, 13% (n=7) included an upgrade of a previously reported variant, 5.5% (n=3) had an upgraded variant and an additional finding, and 7.5% (n=4) had an additional finding.Receipt of parental samples after preliminary reporting influenced variant upgrading in 70% of updated final reports.Conclusion: Our early laboratory experience with URGS suggests that adoption has centered on a pediatric, critically ill population spanning diverse clinical indications.We observed frequent repeat ordering and acquisition of parental samples, supporting the feasibility of integrating URGS into clinical care.In addition, the diagnostic yield supports the potential to inform treatment decisions, with nearly two thirds of individuals receiving a definitive or possible molecular diagnosis.It is notable that preliminary reports were highly concordant with the final reports with differences including variant upgrades and additional findings, supporting the robustness of preliminary positive results.Collectively, this experience of a commercial laboratory with URGS offers a real-world perspective into the feasibility and potential clinical utility of URGS.