Analysis of Pathogenic Pseudoexons Reveals Novel Mechanisms Driving Cryptic Splicing

Area of Science:

• Molecular Biology
• Genetics
• Bioinformatics

Background:

• Pre-mRNA splicing is vital for genetic disease diagnosis and treatment.
• Pseudoexons (cryptic exons) are rare splicing mutations that create new exons within introns.
• Deep-intronic single nucleotide variants are a common cause of pseudoexons, posing evolutionary questions.

Purpose of the Study:

• To analyze a comprehensive catalogue of reported pseudoexon splice events.
• To identify novel pseudoexon categories and characterize known types.
• To investigate the link between pseudoexons and deep intronic splicing processes like recursive splicing.

Main Methods:

• Compilation and analysis of over 400 published pseudoexon splice events.
• Comparison with datasets of non-canonical splice events.
• Identification of alignments with known deep intronic splice sites.

Main Results:

• Confirmed common pseudoexon mutation types and proposed new categories for rarer types.
• 15.7% of pseudoexons showed splicing activity in non-mutant cells.
• Seven experimentally confirmed recursive splice sites linked to pseudoexons.

Conclusions:

• Deep-intronic variants are a significant driver of pseudoexon formation.
• Pseudoexons are linked to phenomena like recursive splicing, previously suspected but unconfirmed.
• Findings enhance genetic diagnostics and suggest targets for splice-modulating therapies.