Cryptic exon activation causes dystrophinopathy in two Chinese families

Abstract

The X-linked recessive degenerative disease dystrophinopathy results from variants in the DMD gene. Given the large size and complexity of the DMD gene, molecular diagnosis for all dystrophinopathies remains challenging. Here we identified two cryptic exon retention variants caused by intronic single nucleotide variants in dystrophinopathy patients using combined RNA- and DNA-based methods. As one variant was previously unreported, we explored its likely pathogenic mechanism, via bioinformatic prediction for in silico verification of splicing. Then we constructed a minigene system harboring the variant and used morpholino modified antisense oligonucleotides (ASOs) to induce cryptic exon skipping. ASOs treatment corrected the mis-splicing in the mutant minigene system. Our study defines a novel intronic variant that can cause dystrophinopathy, and illustrates a strategy to overcome the aberrant splicing.

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Fig. 1: Dystrophinpathy occurred in two X-linked recessive families.
Fig. 2: Disease-causing mutations in deep intron.
Fig. 3: Splicing functional verification of the c.4518 + 512 t>a mutation.
Fig. 4: RT-PCR analysis of morpholino modified ASOs titration.

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Acknowledgements

The authors wish to thank the patients and their families for their participation. JM wants to thank the patient and support from Ni Xie for these years.

Funding

This study was supported by the National Nature Science Foundation of China (81870902) and the Joint Funds for the innovation of science and Technology, Fujian province (2018Y91030173).

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Correspondence to Ning Wang or Zhi-Qiang Wang.

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The authors declare that they have no conflict of interest.

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Jin, M., Li, J., Xu, G. et al. Cryptic exon activation causes dystrophinopathy in two Chinese families. Eur J Hum Genet (2020). https://doi.org/10.1038/s41431-020-0578-z

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