Antisense suppression of donor splice site mutations in the dystrophin gene transcript

Area of Science:

• Genetics
• Molecular Biology
• Neurology

Background:

• Duchenne muscular dystrophy (DMD) is a severe genetic disorder caused by mutations in the dystrophin gene.
• Splice site mutations can lead to non-functional dystrophin mRNA, contributing to DMD pathogenesis.
• Understanding the precise impact of splice site mutations is crucial for developing targeted therapies.

Purpose of the Study:

• To characterize two novel donor splice site mutations in the dystrophin gene leading to DMD.
• To evaluate the efficacy of splice-switching antisense oligomers (SSOs) in correcting these specific mutations.
• To explore the potential of SSO-based therapies for Duchenne muscular dystrophy.

Main Methods:

• Identification and characterization of splice site mutations in dystrophin exons 16 and 45.
• In vitro and cellular transfection studies using splice-switching antisense oligomers.
• Analysis of dystrophin mRNA splicing, reading frame restoration, and protein expression.

Main Results:

• Two donor splice site mutations in dystrophin exons 16 and 45 were found to cause DMD by inactivating mRNA and retaining introns.
• Targeting exon 16 with SSOs efficiently excised the exon and intron, restoring the reading frame and dystrophin production in vitro.
• Targeting exon 45 showed modest results, but dual targeting of adjacent exons (44/45 or 45/46) improved exon skipping and intron removal.

Conclusions:

• The identified splice site mutations are amenable to antisense oligomer intervention.
• SSOs targeting specific splice sites offer a potential therapeutic strategy for DMD caused by these mutations.
• Case-by-case evaluation of splice site mutations is recommended for personalized oligomer-based therapeutic approaches.