Summary: A new genomic diagnostics study has introduced an innovative “RNA origami” technique to accurately identify and measure high-stakes genetic errors. The research addresses a critical diagnostic blind spot: repeat expansion disorders, such as forms of muscular dystrophy, Huntingtonโs disease, and amyotrophic lateral sclerosis (ALS), which are driven by repetitive sequences that multiply far beyond their normal length.
By stretching fragile RNA samples into labeled, usable nanostructures and passing them through microscopic glass holes called nanopores, the team achieved an unprecedented resolution capable of instantly distinguishing healthy tissue from disease state thresholds using only minuscule clinical samples.
Key Facts
- The Undiagnosed 90%: Repeat expansion disorders disrupt cellular machinery and affect approximately 1 in every 280 people globally. However, due to a severe lack of fast, affordable, and precise sizing tests, up to 90% of individuals living with these conditions remain entirely undiagnosed.
- The Crucial Threshold Baseline: Sizing these expansions is paramount because symptom severity and disease onset depend directly on the length of the repeat. For example, 50 repeats in the DMPK gene signal mild adult muscular dystrophy, but any further increase drastically raises the risk of severe congenital forms. In central hypoventilation syndrome, a tiny variation of just six repeats dictates whether a newborn breathes normally or suffers fatal respiratory failure during sleep.
- The Failure of PCR and Standard Sequencing: Traditional diagnostic auditing relies on Polymerase Chain Reaction (PCR), which notoriously distorts the true physical length of repeated loops. Meanwhile, modern genetic sequencing technology frequently encounters systemic reading errors inside highly repetitive zones.
- The Electrical Origami Loop: Collaborating with the University of Belgrade in Serbia, Cambridge physicists used short DNA strands to fold fragile RNA molecules into stable, structural shapes. As these nanostructures flow through a microscopic glass nanopore, they block a baseline current, producing an exact electrical signal pattern that matches the shape and number of repeats.
- Elite 18-Nucleotide Resolution: The RNA origami technique achieved an extraordinary diagnostic resolution of just 18 nucleotides (the fundamental chemical building blocks of RNA and DNA). This provides more than enough precision to isolate healthy baselines from dangerous expansions using minimal patient material.
- Commercial Scaling Horizon: While the molecular platform is currently validated in laboratory-controlled environments, the university spin-out company Cambridge Nucleomics is actively engineering the technology into a commercial diagnostics platform. The next step requires scaling multiple nanopores to run in parallel to process clinical patient samples at routine diagnostic speeds.
Source: University of Cambridge
Researchers have developed a technique that can identify errors caused by mutations linked to a range of genetic disorders, including forms of muscular dystrophy, Huntingtonโs disease and amyotrophic lateral sclerosis (ALS), which could accelerate accurate diagnosis of these conditions.
The technique, developed by researchers led by the University of Cambridge, uses RNA samples stretched into usable shapes and tiny glass holes known as nanopores, to analyse sections of RNA that have multiplied far beyond their normal length.
These expanded stretches interrupt the cellโs machinery and can trigger conditions known as repeat expansion disorders, which affect approximately one in every 280 people. Scientists say that as many of 90% of people with these disorders are undiagnosed, which poses the need for a fast and affordable test for sizing the repeats.
The genomic DNA in our cells contains many stretches of simple repetitive sequences, but in repeat expansion disorders, the size of the expansion will often affect the onset and severity of the disease. However, measuring these expansions is notoriously difficult.
โRNA is incredibly informative in terms of what it can tell you about the disorders we want to study, but itโs also incredibly fragile and often challenging to study,โ said lead author Gerardo PatiรฑoโGuillรฉn, from Cambridgeโs Cavendish Laboratory.
โCurrent techniques were designed for DNA, so they often lose the information in RNA that signals disease. We wanted to fix that.โ
Measuring tandem repeat expansions usually relies on polymerase chain reaction (PCR), which many people will recall from the Covid-19 pandemic. However, PCR can distort the true length of the repeated section, while newer sequencing methods frequently encounter errors in the repeated sections.
Accurately sizing repeat expansions is important for diagnosis, because symptoms often depend on how large the repeat region has become. For example, people with around 50 repeats in the DMPK gene โ the threshold for myotonic dystrophy type 1, the most common muscular dystrophy in adults โ may only have mild symptoms. But any further increase in repeated sections can significantly raise the risk of a more severe form of the disease, which could be passed down to children.
In congenital central hypoventilation syndrome, another repeat expansion disorder, a difference of only six repeats can determine whether a newborn baby has normal breathing control or experiences dangerous respiratory failure during sleep.
Working with colleagues from the University of Belgrade in Serbia, the Cambridge researchers stretched RNA molecules into labelled nanostructures using short pieces of DNA, then passed the structures through a nanopore.
As the molecules travelled through the pore, they produced an electrical signal whose pattern corresponded to the RNAโs shape, including how many repeats it contained.
This RNA origami method achieved a resolution of just 18 nucleotides โ the essential building blocks of RNA and DNAโ enough to tell apart healthy and diseaseโassociated repeat section.
Theย resultsย are reported in the journalย Nature Communications.
PatiรฑoโGuillรฉn says the ability to detect such subtle differences with minimal RNA is particularly important given the tiny amounts of patient material often available in clinical settings. โOne of the reasons our collaborators in Serbia were interested is that we only need extremely small amounts of RNA to get a good result,โ he said.
While the team have achieved promising results, in the lab, they are hoping to improve their technology to the point where it can be scaled to a commercial platform. The team has not yet tested patient samples, and the platform must be scaled up so that many nanopores operate in parallel โ a prerequisite for producing results fast enough for routine diagnostics.
The University spinโout company Cambridge Nucleomics, coโfounded by senior author Professor Ulrich Keyser, also from the Cavendish Laboratory, is developing the method into a diagnostics platform.
While the technique is unlikely to immediately replace routine PCR-based diagnostic tests, it could complement sequencing technology by providing fast, targeted tests capable of sizing the expansion for families known to carry repeatโexpansion disorders, or for clinicians needing quick answers.
In the longer term, PatiรฑoโGuillรฉn sees potential for monitoring the response on disease-modifying therapies that are expected to be approved for repeat expansion disorders in the coming years.
โWe have a very strong molecular platform,โ he said. โWeโre confident about what it can do in controlled samples. The next challenge is proving it works just as well in clinical material.โ
Funding: The research was supported in part by the European Research Council, the European Union, and the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI). Gerardo Patiรฑo-Guillรฉn is a Member of Churchill College, Cambridge.
Key Questions Answered:
A: Because repeating genetic sequences are the ultimate cloaking device for standard laboratory machines. Traditional DNA tests like PCR act like a photocopier; when they encounter a phrase that repeats hundreds of times, the machine slips, stutters, and distorts the true length of the section. Since the severity of diseases like muscular dystrophy or ALS depends entirely on exactly how long that repetition has grown, these minor reading errors cause thousands of patients to completely slip through the diagnostic cracks.
A: RNA is incredibly informative but notoriously fragile and hard to handle. The Cambridge team solved this by using short pieces of DNA like structural staples, stretching the fragile RNA into a stable, highly predictable geometric shape. They then pull this labeled nanostructure through a microscopic glass hole called a nanopore. As the shape squeezes through, it disrupts an active electrical current. The unique dipping pattern of that electricity functions like a structural barcode, telling scientists exactly how many repeats the molecule contains.
A: Not immediately. In its current laboratory stage, the platform is a highly precise, targeted tool rather than a mass-production replacement for basic PCR. Its immediate superpower is acting as a fast, targeted check for clinicians who need rapid answers or for families who already know they carry a repeat expansion disorder. In the long term, as the university spin-out Cambridge Nucleomics scales the system to run thousands of nanopores at once, it will also be used to monitor how effectively brand-new, disease-modifying therapies are working inside a patient’s cells.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this genetics and neurology research news
Author:ย Sarah Collins
Source:ย University of Cambridge
Contact:ย Sarah Collins โ University of Cambridge
Image:ย The image is credited to Neuroscience News
Original Research:ย Open access.
โQuantification of disease-associated RNA tandem repeats by nanopore sensingโ by Gerardo Patiรฑo-Guillรฉn, Jovan Peลกoviฤ, Marko Paniฤ, Max Earle, Anastasija Ninkoviฤ, Sergiu Petruศca, Duลกanka Saviฤ-Paviฤeviฤ, Ulrich F. Keyser & Filip Boลกkoviฤ.ย Nature Communications
DOI:10.1038/s41467-026-72819-5
Abstract
Quantification of disease-associated RNA tandem repeats by nanopore sensing
Short tandem repeat expansions underlie a class of neurological and neuromuscular diseases known as repeat expansion disorders, yet the precise characterisation of these repeats remains technically challenging.
Conventional amplification-based methods fail to resolve repeat length accurately due to amplification bias and sequence homogeneity.
Here, we present a single-molecule nanopore-based strategy that enables direct quantification of tandem repeats in native RNA.
By assembling RNA:DNA nanostructures that encode specific repeat number, we achieve repeat size discrimination with a resolution of 18 nucleotides.
Using tandem repeat-containing RNA, we successfully detect and discriminate disease-relevant repeat lengths associated with myotonic dystrophy types 1 (DM1) and 2 (DM2), and congenital central hypoventilation syndrome-1.
Finally, we apply our method to total RNA extracted from a DM1 human cell line model, demonstrating its compatibility with complex biological samples. Our approach offers a platform for studying repeat expansion biology at the single-molecule level, with broad implications for diagnostics, clinical research and multiplexed repeat profiling.
