Functional analysis of splicing mutations in MYO7A and USH2A genes

Area of Science:

• Genetics
• Ophthalmology
• Audiology

Background:

• Usher syndrome is a genetic disorder characterized by sensorineural hearing loss and retinitis pigmentosa.
• Mutations in MYO7A and USH2A genes are primary causes of Usher syndrome types I and II, respectively.
• The pathogenicity of splice-site variants requires further investigation.

Purpose of the Study:

• To analyze five putative splice-site variants in MYO7A and USH2A genes.
• To determine the functional impact of these variants on gene splicing.
• To confirm the pathogenic nature of these variants in Usher syndrome.

Main Methods:

• Bioinformatic analysis of splice-site variants.
• Hybrid minigene assays to study transcript expression.
• Analysis of variants: c.2283-1G>T, c.5856G>A (MYO7A), and c.1841-2A>G, c.2167+5G>A, c.5298+1G>C (USH2A).

Main Results:

• All five analyzed variants abolished the consensus splice site, leading to exon skipping.
• A novel donor splice site was identified for the c.2167+5G>A variant in USH2A.
• The study confirmed the pathogenic role of all five splice-site variants.

Conclusions:

• The analyzed splice-site variants in MYO7A and USH2A are pathogenic.
• Splicing alterations do not directly correlate with Usher syndrome phenotypic differences.
• Genotype-phenotype correlations could not be inferred from these splicing mutations.