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Small nuclear RNA genes in Mendelian disorders

Abstract

Small nuclear RNA (snRNA) genes represent a class of non-protein-coding genes involved in the processing of pre-mRNAs of intron-containing genes. The human genome contains approximately 2,000 snRNA genes; the majority are pseudogenes, and only a small fraction are functional. These snRNAs undergo extensive post-transcriptional modifications, and, together with proteins and other snRNAs, form small nuclear ribonucleoproteins, which are components of the spliceosome. This Review discusses high-impact variants in 12 snRNA genes that cause Mendelian disorders with either autosomal dominant or recessive inheritance patterns. The associated phenotypes include mainly neurodevelopmental delay, developmental abnormalities and retinitis pigmentosa. The presumed consequences of these variants are presented on the basis of previous functional characterization of the corresponding snRNAs. It is anticipated that the understanding of both Mendelian and complex traits due to snRNAs will increase the diagnostic potential, partially explain penetrance and provide more therapeutic options.

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Fig. 1: Simplified schematic representation of the splicing of major introns and the assembly of various snRNPs into a spliceosome.
Fig. 2: Schematic representation of pathogenic variants in the secondary structure of RNU4-2 and RNU6-1 snRNAs in the B complex.
Fig. 3: Schematic representation of pathogenic variants in the secondary structure of the human snRNAs U2, U6, U4 and U5 within the B complex of the major spliceosome.
Fig. 4: Schematic representation of pathogenic variants in the secondary structure of U4atac and U6atac snRNAs in the minor spliceosome.

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Acknowledgements

I thank the ChildCare Foundation for support and colleagues at the Department of Genetic Medicine and Development of the Medical Faculty of the University of Geneva and Medigenome, the Swiss Institute of Genomic Medicine, for discussions. I thank C. Rivolta, D.A. Brow and R.S. Pillai for constructive comments on the manuscript.

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Correspondence to Stylianos E. Antonarakis.

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S.E.A. is a cofounder and the CEO of Medigenome, Swiss Institute of Genomic Medicine, and is also a member of the scientific advisory board of the Imagine Institute of the Necker Hospital in Paris, France.

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Antonarakis, S.E. Small nuclear RNA genes in Mendelian disorders. Nat Genet 58, 28–38 (2026). https://doi.org/10.1038/s41588-025-02440-7

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