RNU4-2 Gene Mutations Cause Common Intellectual Disability
Author: Icahn School of Medicine at Mount Sinai
Published: 2 Jun 2024 - Updated: 8 Nov 2026
Publication Details: Peer-Reviewed | Research, Study, Analysis
Table of Contents:
Synopsis - Definition - Overview - FAQs - Insights, Updates - Related Content
Synopsis
This research, published in the peer reviewed journal Nature Medicine on May 31, 2024, by researchers at the Icahn School of Medicine at Mount Sinai with the University of Bristol, KU Leuven and the NIHR BioResource, found that mutations in a tiny non-coding gene called RNU4-2 cause a neurodevelopmental disorder affecting tens of thousands of people worldwide. Comparing whole-genome data from 5,529 people with intellectual disability and 46,401 controls in the UK's National Genomic Research Library, the team found the condition ranks second only to Rett syndrome among patients sequenced by the UK Genomic Medicine Service. The finding can end long diagnostic searches for many families and shows the value of looking beyond protein-coding genes.*
At a Glance
- 1 - RNU4-2 is only 141 units long but plays a key role in gene splicing.
- 2 - The mutations are usually spontaneous rather than inherited from a parent.
- 3 - The study compared rare variants in 41,132 non-coding genes between cases and controls.
- 4 - More than 99 percent of genes known to cause neurodevelopmental disorders code for proteins.
Topic Definition
- Non-Coding Gene
A non-coding gene is a stretch of DNA that is copied into RNA but does not carry instructions for making a protein. The RNA it produces, such as the small nuclear RNA made by RNU4-2, often helps control how other genes are processed or used, for example in splicing, and mutations in these genes can cause disease even though no protein is changed.
Overview
Researchers at the Icahn School of Medicine at Mount Sinai and others have identified a neurodevelopmental disorder, caused by mutations in a single gene, that affects tens of thousands of people worldwide. The work, published in the May 31, 2024, online issue of Nature Medicine, was done in collaboration with colleagues at the University of Bristol, UK; KU Leuven, Belgium; and the NIHR BioResource, currently based at the University of Cambridge, UK. The findings will improve clinical diagnostic services for patients with neurodevelopmental disorders.
Through rigorous genetic analysis, the researchers discovered that mutations in a small non-coding gene called RNU4-2 cause a collection of developmental symptoms that had not previously been tied to a distinct genetic disorder. Non-coding genes are parts of DNA that do not produce proteins. The investigators used whole-genome sequencing data in the United Kingdom's National Genomic Research Library to compare the burden of rare genetic variants in 41,132 non-coding genes between 5,529 unrelated cases with intellectual disability and 46,401 unrelated controls.
The discovery is significant, as it represents one of the most common single-gene genetic causes of such disorders, ranking second only to Rett syndrome among patients sequenced by the United Kingdom's Genomic Medicine Service. Notably, these mutations are typically spontaneous and not inherited, providing important insights into the nature of the condition.
"We performed a large genetic association analysis to identify rare variants in non-coding genes that might be responsible for neurodevelopmental disorders," says the study's first author Daniel Greene, PhD, Assistant Professor of Genetics and Genomic Sciences at Icahn Mount Sinai and a Visitor at the University of Cambridge. "Nowadays, finding a single gene that harbors genetic variants responsible for tens of thousands of patients with a rare disease is exceptionally unusual. Our discovery eluded researchers for years due to various sequencing and analytical challenges."
More than 99 percent of genes known to harbor mutations that cause neurodevelopmental disorders encode proteins. The researchers hypothesized that non-coding genes, which don't produce proteins, could also host mutations leading to intellectual disability. Neurodevelopmental disorders, which often appear before grade school, involve developmental deficits affecting personal, social, academic, or occupational functioning. Intellectual disability specifically includes significant limitations in intellectual functioning (e.g., learning, reasoning, problem-solving) and adaptive behavior (e.g., social and practical skills).
"The genetic changes we found affect a very short gene, only 141 units long, but this gene plays a crucial role in a basic biological function of cells, called gene splicing, which is present in all animals, plants and fungi," says senior study author Ernest Turro, PhD, Associate Professor of Genetics and Genomic Sciences at Icahn Mount Sinai and a Visitor at the University of Cambridge. "Most people with a neurodevelopmental disorder do not receive a molecular diagnosis following genetic testing. Thanks to this study, tens of thousands of families will now be able to obtain a molecular diagnosis for their affected family members, bringing many diagnostic odysseys to a close."
Next, the researchers plan to explore the molecular mechanisms underlying this syndrome experimentally. This deeper understanding aims to provide biological insights that could one day lead to targeted interventions.
"What I found remarkable is how such a common cause of a neurodevelopmental disorder has been missed in the field because we've been focusing on coding genes," says Heather Mefford, MD, PhD, of the Center for Pediatric Neurological Disease Research at St. Jude Children's Research Hospital who was not involved with the research. "This study's discovery of mutations in non-coding genes, especially RNU4-2, highlights a significant and previously overlooked cause. It underscores the need to look beyond coding regions, which could reveal many other genetic causes, opening new diagnostic possibilities and research opportunities."
About The Paper
The paper is titled "Mutations in the U4 snRNA gene RNU4-2 cause one of the most prevalent monogenic neurodevelopmental disorders."
Authors
The remaining authors of the paper are Chantal Thys (KU Leuven, Belgium); Ian R. Berry, MD (University of Bristol, UK); Joanna Jarvis, MD (Birmingham Women's Hospital, UK); Els Ortibus, MD, PhD (KU Leuven, Belgium); Andrew D. Mumford, MD (University of Bristol, UK); and Kathleen Freson, PhD (KU Leuven, Belgium).
Funding
The work was supported, in part, by NIH awards R01HL161365 and R03HD111492. See the paper for further details on funding.
Icahn School of Medicine at Mount Sinai
The Icahn School of Medicine at Mount Sinai, located in New York City on the border between the Upper East Side and East Harlem, is internationally renowned for its outstanding research, educational, and clinical care programs. It is the sole academic partner for the eight member hospitals* of the Mount Sinai Health System, one of the largest academic health systems in the United States, providing care to a large and diverse patient population.
* Mount Sinai Health System member hospitals: The Mount Sinai Hospital; Mount Sinai Beth Israel; Mount Sinai Brooklyn; Mount Sinai Morningside; Mount Sinai Queens; Mount Sinai South Nassau; Mount Sinai West; and New York Eye and Ear Infirmary of Mount Sinai.
More on this topic: Cognitive Disability Publications - Disability Types Publications
Frequently Asked Questions
NOTE: Researched FAQs by Disabled World (DW)
What is gene splicing?
Splicing is the step in which a cell cuts out non-coding sections from a gene's RNA copy and joins the remaining parts, so the right protein can be made.
What is a neurodevelopmental disorder?
It is a condition that begins in childhood and affects brain development, such as intellectual disability, autism or ADHD, influencing learning, behavior or communication.
How is intellectual disability diagnosed?
It is diagnosed by assessing intellectual functioning and adaptive skills in daily life, with onset during the developmental period, often supported by genetic testing to find a cause.
What is whole-genome sequencing?
It is a test that reads nearly all of a person's DNA, including non-coding regions that standard gene panels or exome tests can miss.
Can parents pass on RNU4-2 mutations?
The mutations found are usually new in the child and not inherited, so the chance of it happening again in a family is generally low, though a genetic counselor can advise.
Is there a treatment for RNU4-2 related disorder?
There is no specific treatment yet. Care focuses on therapies, education support and managing symptoms such as seizures.
Why does a genetic diagnosis matter if there is no cure?
It can end uncertainty, guide medical monitoring, connect families with support groups and research, and inform future family planning.
How can families ask for genetic retesting?
Families can ask their doctor or genetics clinic whether past results can be reanalyzed or whether genome sequencing is available.
Insights, Analysis, and Developments
Editorial Note: Many families of children with intellectual disability spend years without knowing the cause, even after genetic testing, because tests have focused on genes that make proteins. Finding such a common cause in a small non-coding gene shows how much may still be hidden in the rest of the genome. A diagnosis does not yet bring a specific treatment, but it can connect families with others, guide care and support, inform family planning and open the door to research. Families whose child has an unexplained neurodevelopmental disorder may wish to ask their genetics team whether reanalysis or genome sequencing could now give an answer.*
Attribution/Source(s): This peer-reviewed publication was selected for publishing by the editors of Disabled World (DW) due to its relevance to the disability community. Originally issued as a press release by Icahn School of Medicine at Mount Sinai and published on 2 Jun 2024. Last updated on 8 Nov 2026. This content may have been edited for style, clarity, or brevity.
* Editorial additions by Ian C. Langtree.