Characterization of a Splice-Altering Variant in SCN5A Associated With Brugada Syndrome　- Insights Into Splice Error...

Area of Science:

• Genetics
• Molecular Biology
• Cardiology

Background:

• Brugada syndrome (BrS) is an inherited arrhythmia linked to SCN5A gene dysfunction.
• A novel SCN5A variant, c.1338G>A, was identified in a patient with drug-induced BrS.
• This variant is located in the final codon of exon 10, suggesting a potential impact on RNA splicing.

Purpose of the Study:

• To investigate the splicing alteration caused by the SCN5A c.1338G>A variant.
• To evaluate the efficacy of antisense oligonucleotides (ASOs) in correcting the identified splicing defect.

Main Methods:

• Identification of SCN5A c.1338G>A in patient DNA.
• Prediction of splicing impact using SpliceAI.
• Validation of splicing alteration via minigene assays in HEK-293 cells and iPSC-cardiomyocytes.
• Testing of three ASOs for splice correction efficacy.

Main Results:

• SpliceAI accurately predicted the splice-altering potential of SCN5A c.1338G>A, including cryptic splice site usage.
• Minigene assays confirmed the variant's ability to disrupt normal splicing.
• ASOs demonstrated a capacity to reduce splice error products but failed to restore authentic splicing.

Conclusions:

• The SCN5A c.1338G>A variant is confirmed to cause a splice site alteration leading to Brugada syndrome.
• SpliceAI is a valuable tool for screening potential splice-altering variants in targeted genomic regions.
• Current ASO technology requires further development for effective correction of splicing defects near canonical splice sites.