Key result
A novel heterozygous missense mutation (c.3830G>A, p.Arg1277Gln) in exon 28 of the MYH7 gene was identified as the cause of myosin storage myopathy in three generations of a Chinese family.
Case Report (n=3)
No
The identification of the p.Arg1277Gln mutation in the MYH7 gene in a family with myosin storage myopathy expands the known clinical phenotypes associated with mutations in the rod region of MyHCI, which were previously only linked to cardiomyopathy.
Alerts clinicians to this MYH7 variant in familial cases; extends known mutations but remains hypothesis-generating.
Background Myosin storage myopathy (MSM) is caused by missense mutations in the MYH7 gene, which encodes the β-cardiac/slow skeletal muscle myosin heavy chain rod (MyHCI). MSM is an autosomal dominant/recessive myopathy characterized by subsarcolemmal accumulations of myosin in type I muscle fibers that results in weakness of the scapula, limb and distal muscles.Methods Here, we report a MSM phenotype that was present across three generations of individuals from the same family, one of whom was a neonate.Results At birth, the neonate had an elevated creatine kinase level and decreased muscle tone in the limbs. At 2 months of age, the infant’s cervical vertebrae caused his head to be skewed to the right. At 7 months of age, the infant’s development was delayed.Whole exome sequencing showed a novel heterozygous variant NM_000257.3: c.3830G>A (p.Arg1277Gln) at exon 28 of the MYH7 gene in the DNA of the infant and his father.Conclusions Previously, which site has only been reported in 2 cases of cardiomyopathy; therefore, this study expands our knowledge of the clinical phenotypes associated with mutations within the rod region of MyHCI. Importantly, close follow-up of the neonate will provide important information on the natural history of MSM associated with MYH7 gene mutation.
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Li et al. (2020) conducted a case report in Myosin storage myopathy (n=3). MYH7 gene mutation (NM_000257.3: c.3830G>A, p.Arg1277Gln) was evaluated on Identification of genetic mutation associated with the clinical phenotype. A novel heterozygous missense mutation (c.3830G>A, p.Arg1277Gln) in exon 28 of the MYH7 gene was identified as the cause of myosin storage myopathy in three generations of a Chinese family.
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