Summary: Researchers have developed an innovative genomic diagnostic technique—an “RNA origami” approach—that can precisely identify and quantify dangerous repeat expansion mutations. This method targets a persistent diagnostic blind spot: repeat expansion disorders such as certain muscular dystrophies, Huntington’s disease and amyotrophic lateral sclerosis (ALS). These conditions are driven by simple sequence repeats that grow well beyond their normal length, and accurately sizing them is essential for diagnosis and prognosis.
The approach stabilises fragile RNA by folding it into labelled RNA:DNA nanostructures and threads these structures through a single nanopore in glass. As each nanostructure passes through the pore it alters an ionic current in a repeat-dependent pattern, producing an electrical readout that directly reflects the number and arrangement of repeats from extremely small clinical samples.
Key Facts
- The Undiagnosed Majority: Repeat expansion disorders interfere with normal cellular processes and collectively affect roughly 1 in 280 people. Current diagnostic limitations mean a large proportion of affected individuals—scientists estimate as many as 90%—remain undiagnosed because available tests are either inaccurate, slow, or too costly for routine screening.
- Thresholds Matter: The precise length of a repeat expansion determines disease onset and severity. For example, approximately 50 repeats in the DMPK gene mark the threshold for adult-onset myotonic dystrophy type 1, while modest increases beyond that can produce more severe, congenital forms. In congenital central hypoventilation syndrome, a difference of only six repeats can change whether an infant breathes normally or faces life‑threatening respiratory problems during sleep.
- Limitations of Standard Methods: PCR-based tests and many sequencing platforms often fail to measure repeat lengths accurately. PCR can introduce bias and length distortion during amplification, and conventional sequencing frequently produces errors across long, homogeneous repeat tracts.
- Electrical “Origami” Readout: The Cambridge-led team, working with collaborators at the University of Belgrade, used short DNA oligonucleotides to fold fragile RNA into robust, labelled nanostructures. Passing these constructs through a glass nanopore produces a characteristic blockade of ionic current; the waveform encodes the structure and the number of tandem repeats present.
- 18-Nucleotide Diagnostic Precision: The method attains a repeat-size resolution of just 18 nucleotides, sufficient to distinguish clinically relevant repeat-length categories and to separate normal from disease-associated expansions using minute amounts of RNA.
- Path to Commercialisation: The molecular platform currently performs well in controlled laboratory conditions. The University of Cambridge spin‑out Cambridge Nucleomics is developing the technique into a diagnostic product. Scaling will require running many nanopores in parallel to meet throughput needs for routine clinical use.
Source: University of Cambridge
Overview
The new assay detects and quantifies disease-associated RNA tandem repeats by converting native RNA molecules into predictable, labelled shapes and sensing them with nanopore technology. This single‑molecule approach avoids amplification bias and directly reads repeat length from RNA, offering a complementary strategy to existing DNA-based diagnostics.
Short tandem repeats are abundant in the human genome, but when they expand beyond normal sizes they can disrupt proteins, RNA processing or other cellular systems and produce progressive neurological or neuromuscular disease. Because repeat length often correlates with symptom severity and age of onset, reliable sizing is critical for diagnosis, family counselling and clinical decision-making.
Lead author Gerardo Patiño‑Guillén (Cavendish Laboratory, University of Cambridge) emphasises that RNA carries critical information about disease biology but is delicate and difficult to analyse. “Existing tools were optimised for DNA and frequently lose the disease-relevant information present in RNA,” he explains. This work was motivated by the need to preserve and read that RNA signal accurately.
The team demonstrated the technique on repeat sequences relevant to myotonic dystrophy types 1 and 2 (DM1 and DM2) and congenital central hypoventilation syndrome, and they validated performance on complex biological samples, including total RNA extracted from a DM1 human cell line model.
In the lab, the platform shows strong promise for precise, low-input repeat sizing. Before clinical deployment the method must be tested on clinical patient samples and engineered for higher throughput: multiple nanopores operating in parallel will be required to deliver routine diagnostic turnaround times.
Cambridge Nucleomics, co‑founded by senior author Professor Ulrich Keyser, is advancing development toward a scalable diagnostic instrument. In the near term the assay could serve as a fast, targeted test for families known to carry repeat‑expansion mutations or for clinicians seeking rapid, high‑precision results. Over time it may also become a tool for monitoring patient response to emerging disease‑modifying therapies for repeat expansion disorders.
Funding: The study received partial support from the European Research Council, the European Union, and the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI). Gerardo Patiño‑Guillén is a member of Churchill College, Cambridge.
Key Questions Answered:
A: Repetitive DNA and RNA regions are difficult for standard laboratory methods to handle. Amplification-based tests like PCR introduce length distortion when copying long repeats, and many sequencing platforms struggle to read through highly repetitive stretches without errors. Because clinical outcomes depend on exact repeat length, these measurement errors can prevent accurate diagnosis.
A: The method stabilises fragile RNA by hybridising it with short DNA strands to form a predictable nanostructure. When that labelled structure is driven through a nanopore, it produces a unique pattern of current blockage. That electrical signature serves as a structural barcode that reports the number and arrangement of tandem repeats within the RNA molecule.
A: Not immediately. The technique is currently a precise, targeted tool best suited to confirmatory testing, rapid checks for at‑risk families, or research applications. Widespread clinical use will require parallelisation and further validation on patient material. In the long run, with successful scale-up, it could complement or extend existing diagnostics and support therapeutic monitoring.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The underlying journal paper was reviewed in full.
- Staff added contextual background to explain clinical significance.
About this genetics and neurology research news
Author: Sarah Collins
Source: University of Cambridge
Contact: Sarah Collins – University of Cambridge
Image: The image is credited to Neuroscience News
Original Research: Open access. Quantification of disease-associated RNA tandem repeats by nanopore sensing by Gerardo Patiño-Guillén, Jovan Pešović, Marko Panić, Max Earle, Anastasija Ninković, Sergiu Petrușca, Dušanka Savić-Pavićević, Ulrich F. Keyser & Filip Bošković. DOI:10.1038/s41467-026-72819-5
Abstract
Quantification of disease-associated RNA tandem repeats by nanopore sensing
Short tandem repeat expansions cause a group of neurological and neuromuscular diseases known as repeat expansion disorders, yet precise characterisation of these repeats remains technically difficult. Amplification-based methods suffer from bias and fail to provide accurate repeat lengths. This study introduces a single-molecule nanopore strategy that quantifies tandem repeats directly from native RNA. By assembling RNA:DNA nanostructures that encode repeat number, the method discriminates repeat sizes with an 18-nucleotide resolution. Using repeat-containing RNA, the team detected disease-relevant lengths associated with myotonic dystrophy types 1 and 2 and congenital central hypoventilation syndrome, and demonstrated compatibility with total RNA from a DM1 human cell line. The approach provides a platform for single-molecule study of repeat biology with implications for diagnostics, clinical research and multiplexed repeat profiling.