Myosin storage myopathy associated with a heterozygous missense mutation in MYH7.
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Tajsharghi H, Thornell LE, Lindberg C, Lindvall B, Henriksson KG, Oldfors A
Myosin storage myopathy associated with a heterozygous missense mutation in MYH7.
Ann Neurol. 2003 Oct;54(4):494-500.
- PubMed ID
- 14520662 [ View in PubMed]
- Abstract
Myosin constitutes the major part of the thick filaments in the contractile apparatus of striated muscle. MYH7 encodes the slow/beta-cardiac myosin heavy chain (MyHC), which is the main MyHC isoform in slow, oxidative, type 1 muscle fibers of skeletal muscle. It is also the major MyHC isoform of cardiac ventricles. Numerous missense mutations in the globular head of slow/beta-cardiac MyHC are associated with familial hypertrophic cardiomyopathy. We identified a missense mutation, Arg1845Trp, in the rod region of slow/beta-cardiac MyHC in patients with a skeletal myopathy from two different families. The myopathy was characterized by muscle weakness and wasting with onset in childhood and slow progression, but no overt cardiomyopathy. Slow, oxidative, type 1 muscle fibers showed large inclusions consisting of slow/beta-cardiac MyHC. The features were similar to a previously described entity: hyaline body myopathy. Our findings indicate that the mutated residue of slow/beta-cardiac MyHC is essential for the assembly of thick filaments in skeletal muscle. We propose the term myosin storage myopathy for this disease.