P660: Shades of grey in a binary world: Clinician preferences for appearance of uncertain results in the electronic medical record

treatment, and patient advocacy for rare diseases.These initiatives rely on unified, systematic workflows for achieving molecular diagnoses and novel gene discovery.However, challenges remain in utilizing Mondo to describe rare diseases.For some conditions it is insufficient to assign a singular Mondo label to participants, whereas for other participants, Mondo is lacking crucial disease concepts.Future steps include direct contribution of terms from disease experts to the Mondo initiative.We anticipate the addition of several hundred rare disease terms to describe all participants within the CRDC.Additionally, we expect Mondo terms for undiagnosed participants to change over time as they undergo various genomic studies in pursuit of their genetic diagnoses.Active engagement and feedback from investigators is vital for achieving consensus in rare disease ontology and improving diagnosis of unexplained rare diseases.