25/11/2025
More than half of all rare disease patients still remain undiagnosed even after extensive genetic testing. Yet, as genomic knowledge expands, many of these "unsolved" cases already hold the answers, hidden in existing variant data that was never reanalysed.
Clinical guidelines such as those of the American College of Medical Genetics (ACMG) now recommend systematic reanalysis of whole exome (WES) and whole genome (WGS) data as a routine part of diagnostics. In practice, however, most laboratories struggle to follow these recommendations: manual reanalysis is too time-consuming, too labour-intensive, and too costly.
Arun changes that.
Developed by Codon One in Leuven, Arun is the first software platform designed specifically for fully automated genome reanalysis. It continuously re-examines archived genomic data using the latest gene–disease insights, updated variant classifications, and evolving phenotypic information.
Arun automatically mines clinical notes to extract phenotypes, builds structured HPO profiles, reinterprets variants, and identifies potential diagnoses, all without manual intervention.
In a pilot study at Antwerp University Hospital, Arun identified the causal variant within the top three in 99% of solved cases and reduced the manual review burden by 50%.
"In our centre, Arun prioritised an average of 4.8 variants per case and identified the correct variant among the top three in nearly all solved cases," said Prof. Bart Loeys from the Centre of Medical Genetics, Antwerp University Hospital. "This level of accuracy and automation represents a major step forward for clinical genomics."
Beyond its performance, Arun was designed for scalability: it automatically identifies and prioritises cases most likely to yield a diagnosis, allowing clinical teams to reanalyse thousands of genomes on a routine basis while concentrating their efforts on those with the highest likelihood of being solved.
Capable of analysing an exome in under one minute and a whole genome in under five, Arun is roughly 100 times faster than existing software, setting a new benchmark for clinical-grade speed and precision, and making reanalysis not just a recommendation, but a practical reality.
"Reanalysis saves lives, but rarely happens," said Peter Schols, Founder and CEO of Codon One. "With Arun, that changes. We’re giving undiagnosed patients unlimited second chances."
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About Codon One
Codon One is a genomics software company based in Leuven, Belgium, developing next-generation tools for genome interpretation. Founded by the former creators of Moon — the first AI-driven software for rare disease diagnostics — Codon One’s mission is to end the diagnostic odyssey for rare disease patients through automation, accuracy, and innovation.
Website: https://codon.one
Press contact: peter@codon.one