Broad Clinical Labs, in collaboration with Roche and Boston Children’s Hospital, reported an ultra‑rapid whole‑genome sequencing workflow that produced variant call files in a mean of 4 hours 4 minutes from genomic DNA to analysis, with fastest runs under four hours, per a New England Journal of Medicine publication and ASHG presentation. The speed was enabled by Roche’s Sequencing‑by‑Expansion (SBX) technology and end‑to‑end protocol optimization spanning extraction, library prep and analysis. Investigators stress the result is a proof of concept for same‑day sequencing in acute clinical settings, notably neonatal intensive care, and that further validation is required to confirm robustness, cost and operational feasibility at scale. The team emphasized that achieving such turnaround required coordinated hardware, chemistry and bioinformatics improvements. Clinical adoption will hinge on reproducibility, regulatory clearance of sequencing platforms and integration into hospital workflows, but the demonstration sets a new benchmark for rapid genomic diagnostics in critical care.