Summary
A medRxiv preprint describes a six-site RNA-splicing signature that distinguished 19 people with a specific RNU4-2 variant from study controls. The researchers propose it as a biomarker for therapeutic development, with results so far focused on T-loop variants.
A medRxiv preprint reports a six-site RNA-splicing signature that distinguished 19 people with a specific RNU4-2 variant from 54 controls in the study. The researchers also found no false positives when they applied the signature to a further 5,984 whole-blood controls. They propose it as a quantitative biomarker for therapeutic development; the reported findings are focused on variants in one region of RNU4-2.
ReNU syndrome is a severe neurodevelopmental disorder caused by de novo variants in RNU4-2, a gene that produces the U4 small nuclear RNA. U4 is part of the spliceosome, the cell machinery that processes RNA by joining selected gene segments together. Altered splice-site selection is a molecular feature of the syndrome.
From RNA sequencing to a six-site signature
The researchers analysed RNA-sequencing data from two independent cohorts, comprising 30 people with ReNU syndrome and 54 controls. They identified 483 alternative-splicing events shared across the cohorts. The strongest agreement was among 105 events involving alternative selection of a 5′ splice site, where RNA processing can begin at different positions.
From those events, the team derived a signature using six sites. In the reported analysis, it perfectly distinguished 19 individuals with the RNU4-2 n.64_65insT variant from 54 controls. Applied to a further set of 5,984 whole-blood controls, it produced no false positives.
The researchers report that the signature was specific to variants in the U4 RNA’s T-loop, a structural region associated with greater clinical severity. They also found alternative-splicing events associated with variants in another region, Stem III. This distinction matters because the six-site signature should not be read as a single marker for every pathogenic RNU4-2 variant.
What the results support
The team also examined a patient-derived induced pluripotent stem cell model carrying the recurrent RNU4-2 n.64_64insT variant. These cells were differentiated into cortical neuron-like cells, and the researchers report that the splicing signature was reproduced across the stages of differentiation. This offers a second experimental setting in which to study the molecular pattern, alongside the RNA-sequencing cohorts.
A measurable RNA signature could help researchers assess whether future experimental treatments affect the underlying splicing changes. That makes it a potential tool for preclinical work and, if developed further, clinical therapeutic research. The preprint reports biomarker findings, rather than results from a treatment study or a clinically validated diagnostic test.