New Neurodevelopmental Disorder Discovered

A recent study has uncovered a previously unrecognized neurodevelopmental disorder that appears to be influenced by genetics. This discovery could bring new diagnostic options for countless children and families around the globe.

The disorder, linked to a mutation in the RNU2-2 gene, is characterized as recessive. This means that it requires mutations inherited from both parents to manifest. Interestingly, this particular gene is non-coding; rather than producing proteins, it plays a more indirect role within cells.

These two key features—being recessive and non-coding—help clarify why this neurodevelopmental disorder remained undetected for such a long time. Typically, scientists don’t usually look in these regions of DNA for health condition sources.

A team of international researchers became interested in examining RNU2-2 more thoroughly after they identified a dominant mutation of the gene previously linked to a severe brain disorder, which, while notable, is less common than the newly discovered developmental disorder.

According to geneticist Daniel Greene, one of the study’s co-leads from the Icahn School of Medicine at Mount Sinai in the US, “Our discovery provides families with a clear molecular explanation for their child’s condition, something they’ve often waited years to find.” He goes on to say that this clarity can be incredibly significant for families who have navigated uncertain diagnoses for a long time. Plus, it offers researchers a tangible biological target for potential future treatments.

The newly identified disorder is named ReNU2 syndrome. It results from a deficiency of the U2-2 RNA molecule created by the RNU2-2 gene. While parents may carry a single mutated copy without experiencing symptoms, the condition can develop when two copies combine.

The researchers estimated that ReNU2 syndrome might account for around 10% of recessive neurodevelopmental disorders with known genetic roots, potentially affecting thousands in the UK alone. Symptoms can include developmental delays, limited speech ability, and low muscle tone. Learning difficulties and traits often associated with autism, as well as challenges in walking or movement, may also be present. Each child affected could experience symptoms differently, with issues like epilepsy or respiratory and feeding problems possibly emerging.

To identify ReNU2 syndrome, the researchers analyzed over 110,000 individual genome records from two health research databases. They focused on 14,805 unrelated individuals with neurodevelopmental disorders and compared them to a control group of around 52,861 unrelated individuals without such disorders.

Using statistical algorithms, the team pinpointed non-coding genes related to these disorders and estimated the prevalence of ReNU2 syndrome in the population. They further validated their findings through blood tests on selected patients.

Cornelius Gross, a neuroscientist at the European Molecular Biology Laboratory in Italy, described the discovery as a breakthrough, pointing out that the availability of these variants is more than three times higher compared to the next recessive mutation causing severe neurodevelopmental disorders. He emphasized that this research underscores the importance of non-coding genes as focal points for disease research.

This study not only brings clarity to families affected by the disorder but also holds significance for understanding potential management and prevention strategies for those at risk.

Yet, challenges remain. It will be difficult to deliver treatments effectively to the areas of the brain and cells affected by ReNU2 syndrome. Since this disorder is inherited from birth, it’s also uncertain whether retroactive treatment is feasible.

While specific treatments for recessive ReNU2 syndrome are still in the future, geneticist Ernest Turro from the Icahn School of Medicine suggests that understanding the disorder’s basis in U2-2 RNA loss opens up possibilities for potential gene replacement strategies.

This research appears in Nature Genetics.