The answers families seek may be hiding in the instructions that control the genes.
Each year, hundreds of thousands of children are born with spontaneous genetic mutations that disrupt development, and for many of their families, the search for a diagnosis stretches across years of uncertainty. A consortium of researchers has now found that answers may be concealed not in the genes themselves, but in the regulatory regions surrounding them — stretches of DNA long overlooked by clinical testing. By identifying seven previously unknown variants in these so-called untranslated regions, the team has offered diagnoses to ten families and raised a quiet but consequential question about what medicine has been missing all along.
- More than half of all developmental disorder cases go undiagnosed under current genetic testing, leaving families in a prolonged and exhausting search for answers.
- Standard clinical screening focuses almost entirely on protein-coding DNA, systematically bypassing the regulatory regions that control how genes actually function.
- A multi-institution research team identified seven new disease-causing variants in non-coding regions — six tied to a single gene, MEF2C — that conventional tools would never have detected.
- Ten families received long-sought genetic diagnoses from this work, illustrating the immediate human stakes behind what might otherwise seem like a technical discovery.
- Researchers are now calling for untranslated regions to be incorporated into routine clinical screening, a shift that could meaningfully reduce the number of families left without explanation.
Every year, around 400,000 babies are born with spontaneous DNA mutations that can cause intellectual disability, epilepsy, or heart defects. Their families often spend years cycling through specialists and inconclusive tests — a journey researchers call the diagnostic odyssey — searching for a name for what is happening to their child.
A new study, published in the American Journal of Human Genetics and led by researchers from the Wellcome Sanger Institute, the University of Oxford, and several other institutions, suggests that many of those answers have been hiding in plain sight. The team examined untranslated regions, or UTRs — stretches of DNA that sit adjacent to protein-coding genes and regulate how much protein gets made, when production halts, and where proteins end up in the cell. Seven previously unknown variants in these regions were found to cause developmental disorders in children, six of them affecting a single gene called MEF2C. The study provided genetic diagnoses to ten families who had been searching for years.
The gap this exposes in current clinical practice is striking. Standard genetic testing focuses almost exclusively on protein-coding DNA, and while it solves some cases, it fails in more than half. The researchers found that nearly a quarter of the diagnoses they uncovered in one gene came from non-coding variants that routine screening would never have caught.
For families, a diagnosis is far more than a label. It connects them to support networks, informs decisions about future children, and can open pathways to targeted treatment. Above all, it ends the search. As one clinical geneticist involved in the work noted, receiving a diagnosis can profoundly change a family's life by giving them understanding and access to support they could not previously reach.
If non-coding regions were incorporated into routine clinical screening, the ripple effects could be significant — not only for future patients, but for researchers who might revisit existing genetic archives with new eyes. For families still waiting, the study offers a reorienting possibility: the answers they need may not be missing from the genome, but simply in a part of it that medicine has not yet learned to read.
Every year, roughly 400,000 babies are born with spontaneous mutations in their DNA—changes that happen by chance, not inherited from parents—that disrupt normal development. Some of these children end up with intellectual disability, epilepsy, or heart defects. For decades, families have endured what researchers call a diagnostic odyssey: years of testing, specialist visits, and uncertainty, searching for a name for what is happening to their child.
A new study suggests that answer may lie in a part of the genome that doctors have largely ignored. Researchers from the Wellcome Sanger Institute, the University of Oxford, the University of Exeter, Imperial College London, and Spain's National Center for Cardiovascular Research examined regions of DNA that sit right next to the genes that code for proteins. These stretches, called untranslated regions or UTRs, don't directly build proteins themselves. Instead, they act as regulators—controlling how much protein gets made, when production stops, and where the protein ends up inside the cell. The team found seven previously unknown variants in these regulatory zones that cause developmental disorders in children, and six of them affected a single gene called MEFF2C. The work, published in the American Journal of Human Genetics, gave a genetic diagnosis to ten families who had been searching for answers.
The significance lies in what current clinical practice misses. When doctors test a child's DNA for developmental disorders, they typically focus on the protein-coding regions—the parts of the genome that directly spell out the instructions for building proteins. This approach works well enough that it identifies a cause in some cases. But it fails in more than half of all cases. The researchers found that nearly a quarter of the diagnoses they identified in one particular gene came from variants in the non-coding regions that standard screening never examines. That gap represents thousands of families left without answers.
Dr. Nicky Whiffin, a senior researcher at Oxford's Wellcome Centre for Human Genetics, explained the implication: by looking at these overlooked regions, the team identified variants that would have been invisible to conventional clinical screening. The finding doesn't necessarily mean that a quarter of all developmental disorder diagnoses stem from non-coding variants—the sample was smaller and focused on one gene. But it suggests the potential is substantial enough to warrant a change in how doctors approach genetic testing.
Why does a diagnosis matter so much? For families, it is the difference between isolation and connection. A genetic diagnosis opens doors to support networks, to other families facing the same condition, to information that helps with family planning and decisions about future children. It can point toward treatments tailored to the specific genetic cause. And it ends the exhausting search itself—the repeated appointments, the tests that come back inconclusive, the not-knowing. Dr. Meena Balasubramanian, a clinical geneticist at Sheffield Children's NHS Foundation Trust, noted that receiving a diagnosis allows patients and families to access support and gain understanding, which can profoundly change their lives.
The research emerged from the Deciphering Developmental Disorders study, an ongoing effort to find patterns in the genomes of affected children by comparing their DNA to their parents'. Every person is born with roughly 60 de novo mutations on average, but the vast majority cause no harm. The challenge is identifying which rare variants actually drive disease. By expanding the search beyond protein-coding regions into the regulatory zones that control them, researchers opened a new avenue for discovery.
The implications ripple outward. If untranslated regions are included in routine clinical screening, more families could receive diagnoses. Researchers with existing genetic data might re-examine their archives and find variants they had previously overlooked. The diagnostic odyssey, for some families, might finally end. For others still searching, this work offers hope that the answers they seek may be hiding not in the genes themselves, but in the instructions that control them.
Citações Notáveis
By looking at parts of the genome found next to protein coding regions, we have been able to identify multiple variants that cause developmental disorders that would have been missed by current clinical screening.— Dr. Nicky Whiffin, Wellcome Centre for Human Genetics, University of Oxford
Receiving a diagnosis can allow patients and their families to access support networks and gain a greater understanding of their condition, which can have a huge impact on their lives.— Dr. Meena Balasubramanian, Sheffield Children's NHS Foundation Trust
A Conversa do Hearth Outra perspectiva sobre a história
Why focus on these untranslated regions now? Doctors have been doing genetic testing for years.
Because standard testing only looks at the parts of DNA that directly code for proteins. It's like reading only the main text of a book and ignoring the footnotes and margin notes that explain how to read it. These regulatory regions control whether a protein gets made at all, how much, and where it goes in the cell.
So the mutations in these regions can cause disease even though they're not in the genes themselves?
Exactly. If you disrupt how much MEFF2C protein gets made, or when it stops being made, you can cause the same developmental problems as if you broke the gene itself. The researchers found six different variants doing exactly that.
How many families actually got answers from this?
Ten families in this study. But the real significance is what it reveals about the scale of the problem. Nearly a quarter of the diagnoses they found in one gene came from these non-coding variants. That suggests thousands of families might be missing diagnoses because nobody was looking there.
What changes if a family finally gets a diagnosis?
Everything, really. They stop wondering what's wrong. They can connect with other families facing the same condition. They understand the risks for future children. And they might access treatments designed specifically for that genetic cause instead of just managing symptoms.
Is this going to become standard practice?
That's what the researchers are arguing for. If these regions are included in routine clinical screening, more people get diagnosed. But it requires changing how labs do their work, and that takes time.