Thick filament diseases.

Area of Science:

• Genetics
• Molecular Biology
• Neurology

Background:

• Hereditary myosin myopathies are a class of genetic disorders stemming from mutations in skeletal muscle myosin heavy chain (MyHC) genes.
• These myopathies exhibit a spectrum of clinical presentations, including prenatal arthrogrypotic syndromes and progressive adult-onset muscle weakness.

Purpose of the Study:

• To summarize clinical findings, muscle morphology, and molecular genetics of hereditary myosin myopathies.
• To review the impact of mutations in different MyHC isoforms (MYH7, MYH2, MYH3, MYH8) on skeletal and cardiac muscle function.

Main Methods:

• Review of clinical data, muscle pathology reports, and genetic analyses from hereditary myosin myopathy cases.
• Analysis of reported mutations in specific myosin heavy chain (MyHC) isoforms, including MYH7, MYH2, MYH3, and MYH8.

Main Results:

• Mutations in MYH7 are linked to Laing distal myopathy and myosin storage myopathy, with some cases showing cardiac involvement.
• MYH2 mutations are associated with congenital joint contractures and external ophthalmoplegia.
• Mutations in developmental MyHC isoforms (MYH3, MYH8) cause distal arthrogryposis syndromes.

Conclusions:

• Hereditary myosin myopathies encompass a range of skeletal muscle disorders caused by distinct MyHC gene mutations.
• Understanding the genotype-phenotype correlations is crucial for diagnosing and managing these diverse myopathies.