ATP7B variant c.1934T > G p.Met645Arg causes Wilson disease by promoting exon 6 skipping

Area of Science:

• Genetics
• Molecular Biology
• Biochemistry

Background:

• Wilson disease is a genetic disorder affecting copper metabolism due to ATP7B gene mutations.
• The variant c.1934T>G (Met645Arg) is common in Spanish Wilson disease patients but its pathogenicity is debated.
• Previous functional studies yielded conflicting results regarding the variant's impact on protein function.

Purpose of the Study:

• To elucidate the mechanistic effect of the ATP7B variant c.1934T>G on gene function.
• To resolve the controversy surrounding the pathogenicity of the c.1934T>G variant.
• To provide a basis for developing genetic medicines for Wilson disease.

Main Methods:

• Minigene splicing assay.
• Gene-edited HepG2 cells.
• Analysis of exon skipping, frameshift, and stop-gain mutations.

Main Results:

• The c.1934T>G variant induced approximately 70% skipping of exon 6 in the ATP7B gene.
• Exon 6 skipping resulted in a frameshift and a premature stop codon.
• This mechanistic effect leads to a loss of ATP7B function, confirming pathogenicity.

Conclusions:

• The variant c.1934T>G is pathogenic due to its impact on ATP7B splicing.
• This study clarifies the molecular mechanism underlying the variant's contribution to Wilson disease.
• Findings support the development of splice-correcting genetic therapies for Wilson disease.