NOVEL intronic CAPN3 Roma mutation alters splicing causing RNA mediated decay

Area of Science:

• Genetics
• Molecular Biology
• Biochemistry

Background:

• Limb girdle muscular dystrophy (LGMD) is a group of inherited muscle-wasting diseases.
• Calpain 3 (CAPN3) is a key protein implicated in muscle function, and mutations in its gene are a common cause of LGMD2B.
• Accurate diagnosis relies on identifying specific genetic mutations and understanding their functional consequences.

Observation:

• A novel mutation (c.1992 + 2T>G) in the CAPN3 gene was identified.
• This mutation disrupts the normal splicing of intron 17, leading to the exclusion of exon 17.
• The mutation significantly alters mRNA 3D structure, suggesting no-go mRNA decay as the degradation pathway.

Findings:

• The identified CAPN3 mutation severely reduces or eliminates detectable mRNA levels.
• The mechanism of RNA degradation appears to be no-go mRNA decay due to altered mRNA structure.
• This mutation was found in two unrelated Roma individuals, indicating a potential founder effect.

Implications:

• This finding represents the first reported CAPN3 mutation in the Roma population.
• Characterizing this novel mutation improves diagnostic capabilities for limb girdle muscular dystrophy.
• Understanding the molecular mechanism provides insights into CAPN3-related muscle disease pathogenesis.