ABSTRACT
In tyrosinaemia type 1(HT1), a mosaic pattern of fumarylacetoacetase (FAH) immunopositive or immunonegative nodules in liver tissue has been reported in many patients. This aspect is generally explained by a spontaneous reversion of the mutation into a normal genotype. In one HT1 patient carrying the frequent FAH c.1062+5G>A mutation, a second somatic change (c.1061C>A) has been reported in the same allele, and found in immunopositive nodules. Here, we demonstrated that the c.1062+5G>A prevents usage of the exon 12 5′ splice site (ss), even when forced by an engineered U1snRNA specifically designed on the FAH 5′ss to strengthen its recognition. Noticeably the new somatic c.1061C>A change, in linkage with the c.1062+5G>A mutation, partially rescues the defective 5′ss and is associated to trace level (~5%) of correct transcripts. Interestingly, this combined genetic condition strongly favored the rescue by the engineered U1snRNA, with correct transcripts reaching up to 60%. Altogether, these findings elucidate the molecular basis of HT1 caused by the frequent FAH c.1062+5G>A mutation, and demonstrate the compensatory effect of the c.1061C>A change in promoting exon definition, thus unraveling a rare mechanism leading to FAH immune-reactive mosaicism.
Log in or create a free account to read this content
Gain free access to this article, as well as selected content from this journal and more on nature.com
or
References
Lindblad B, Lindstedt S, Steen G. On the enzymic defects in hereditary tyrosinemia. Proc Natl Acad Sci USA. 1977;74:4641–5.
Grompe M, St-Louis M, Demers SI, al-Dhalimy M, Leclerc B, Tanguay RM. A single mutation of the fumarylacetoacetate hydrolase gene in French Canadians with hereditary tyrosinemia type I. N Engl J Med. 1994;331:353–7.
Rootwelt H, Kristensen T, Berger R, Høie K, Kvittingen EA. Tyrosinemia type 1—complex splicing defects and a missense mutation in the fumarylacetoacetase gene. Hum Genet. 1994;94:235–9.
Pérez-Carro R, Sánchez-Alcudia R, Pérez B, Navarrete R, Pérez-Cerdá C, Ugarte M, Desviat LR. Functional analysis and in vitro correction of splicing FAH mutations causing tyrosinemia type I. Clin Genet. 2014;86:167–71.
Bliksrud YT, Brodtkorb E, Andresen PA, van den Berg IE, Kvittingen EA. Tyrosinaemia type I—de novo mutation in liver tissue suppressing an inborn splicing defect. J Mol Med. 2005;83:406–10.
Tajnik M, Rogalska ME, Bussani E, Barbon E, Balestra D, Pinotti M, Pagani F. Molecular basis and therapeutic strategies to rescue factor IX variants that affect splicing and protein function. PLoS Genet. 2016;12:e1006082.
Balestra D, Barbon E, Scalet D, Cavallari N, Perrone D, Zanibellato S, Bernardi F, Pinotti M. Regulation of a strong F9 cryptic 5′ss by intrinsic elements and by combination of tailored U1snRNAs with antisense oligonucleotides. Hum Mol Genet. 2015;24:4809–16.
Cavallari N, Balestra D, Branchini A, Maestri I, Chuamsunrit A, Sasanakul W, Mariani G, Pagani F, Bernardi F, Pinotti M. Activation of a cryptic splice site in a potentially lethal coagulation defect accounts for a functional protein variant. Biochim Biophys Acta. 2012;1822:1109–13.
Roca X, Krainer AR, Eperon IC. Pick one, but be quick: 5′ splice sites and the problems of too many choices. Genes Dev. 2013;27:129–44.
Kvittingen EA, Rootwelt H, Berger R, Brandtzaeg P. Self-induced correction of the genetic defect in tyrosinemia type I. J Clin Invest. 1994;94:1657–61.
Hirschhorn R. In vivo reversion to normal of inherited mutations in humans. J Med Genet. 2003;40:721–8.
Sterne-Weiler T, Howard J, Mort M, Cooper DN, Sanford JR. Loss of exon identity is a common mechanism of human inherited disease. Genome Res. 2011;21:1563–71.
Fernandez Alanis E, Pinotti M, Dal Mas A, Balestra D, Cavallari N, Rogalska ME, Bernardi F, Pagani F. An exon-specific U1 small nuclear RNA (snRNA) strategy to correct splicing defects. Hum Mol Genet. 2012;21:2389–98.
Scalet D, Balestra D, Rohban S, Bovolenta M, Perrone D, Bernardi F, Campaner S, Pinotti M. Exploring splicing-switching molecules for seckel syndrome therapy. Biochim Biophys Acta. 2017;1863:15–20.
Balestra D, Scalet D, Pagani F, Rogalska ME, Mari R, Bernardi F, Pinotti M. An exon-specific U1snRNA induces a robust factor IX activity in mice expressing multiple human FIX splicing mutants. Mol Ther Nucleic Acids. 2016;5:e370.
Acknowledgements
The study was supported by grants from the Telethon Foundation (GGP14190 to MP and DB), the AMC Foundation (to SFJvdG) and the University of Ferrara.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflict of interest
The authors declare that they have no conflict of interest.
Rights and permissions
About this article
Cite this article
Scalet, D., Sacchetto, C., Bernardi, F. et al. The somatic FAH C.1061C>A change counteracts the frequent FAH c.1062+5G>A mutation and permits U1snRNA-based splicing correction. J Hum Genet 63, 683–686 (2018). https://doi.org/10.1038/s10038-018-0427-x
Received:
Revised:
Accepted:
Published:
Issue date:
DOI: https://doi.org/10.1038/s10038-018-0427-x
This article is cited by
-
OTC intron 4 variations mediate pathogenic splicing patterns caused by the c.386G>A mutation in humans and spfash mice, and govern susceptibility to RNA-based therapies
Molecular Medicine (2021)
-
Somatic genetic rescue in Mendelian haematopoietic diseases
Nature Reviews Genetics (2019)
