University of Pennsylvania investigators reported meaningful clinical benefits from an mRNA-based CRISPR base-editing treatment in a single patient case, involving “Baby KJ” with CPS1 deficiency. The patient received directly delivered base editing to correct the CPS1 gene in liver cells, allowing the child to eat a normal protein-filled diet. The report frames the intervention as an expanded-access IND for a single patient delivered as clinical care, not a randomized trial, according to Kiran Musunuru. Musunuru said the case was “unambiguously not a cure,” but he characterized it as a demonstration of what is feasible with current genome editing delivery approaches. The update is likely to re-energize discussion around regulatory pathways for early genome-editing applications as more companies push base editing systems into clinical studies.