Broad Clinical Labs, working with Roche and Boston Children’s Hospital, demonstrated an ultra-rapid whole-genome sequencing workflow that produces diagnostic-ready variant files in about four hours, reporting a mean turnaround of 4 hours 4 minutes and a fastest run under four hours. The result, published in the New England Journal of Medicine and presented at ASHG, used Roche’s Sequencing-by-Expansion (SBX) prototype and tightened every step from extraction to analysis. Broad sequenced and analyzed 15 human genomes, including neonatal ICU samples, showing the workflow’s potential for same‑day genomic diagnosis in critically ill infants. Researchers emphasized the optimization across preanalytical and computational steps rather than any single breakthrough instrument change. The team framed the achievement as a benchmark for clinical genomics speed while cautioning that wider clinical deployment will require validation of robustness, cost and supply-chain considerations for SBX’s commercial rollout. Clarification: Sequencing-by-Expansion (SBX) is Roche’s emerging short-read chemistry platform that expands read information to improve mapping and variant calling while supporting faster instrument runtimes.