Novel sequence variants in dysferlin-deficient muscular dystrophy leading to mRNA decay and possible C2-domain...

Area of Science:

• Genetics
• Molecular Biology
• Neuromuscular Disorders

Background:

• Limb girdle muscular dystrophy 2B and Miyoshi myopathy are autosomal recessive disorders caused by mutations in the dysferlin (DYSF) gene.
• Dysferlin plays a critical role in skeletal muscle membrane repair.
• The DYSF gene comprises 55 exons and spans 150 kb of genomic DNA.

Observation:

• Three families presented with novel sequence variants in the DYSF gene.
• Affected individuals exhibited limb girdle weakness.
• Immunohistochemistry revealed reduced or absent dysferlin protein in affected family members.

Findings:

• Genomic sequencing identified five novel DYSF variants: two missense, one splice-site, one nonsense, and one 3'UTR variant.
• Alterations were confirmed and absent in 400 control alleles.
• Consequences included nonsense-mediated RNA decay, altered protein structure, dysferlin aggregation, and protein deficiency.

Implications:

• These findings expand the spectrum of known DYSF mutations associated with muscular dystrophies.
• Understanding these variants aids in diagnosing and potentially treating dysferlinopathies.
• Elucidates mechanisms of DYSF dysfunction in skeletal muscle membrane repair.