Abstract
BackgroundLaing distal myopathy is a rare autosomal dominant inherited distal myopathy caused by mutations of the MYH7 gene affecting mainly the rod region. We described the clinical features, muscle MRI and pathological changes as well as genetic mutations in a group of Chinese patients with Laing distal myopathy.ResultsSix patients with the confirmed diagnoses of Laing distal myopathy were recruited. Ankle dorsiflexion and finger extension weakness, as well as neck flexion weakness were common in our patients. Myopathic as well as neurogenic lesions were suggested by electromyography in different patients. Respiratory abnormality of sleep apnea was detected in two of our patients stressing the necessity of close respiratory monitoring in this disease. Muscle MRIs showed similar features of concentric fatty infiltration of anterior thigh muscles together with early involvement of tibialis anterior and extensor hallucis longus. However, muscle pathological presentations were varied depending on the biopsied muscles and the severity of the disease. In-frame deletions of the MYH7 gene made up 3/4 of mutations in our patients, suggesting that these are common mutations of Laing distal myopathy.ConclusionsOur study further expanded the phenotypes and genotypes of Laing distal myopathy. In-frame deletions of the MYH7 gene are common causes of Laing distal myopathy.
Highlights
Laing distal myopathy is a rare autosomal dominant inherited distal myopathy caused by mutations of the MYH7 gene affecting mainly the rod region
Slow/β-cardiac myosin heavy chain (MyHC) can be divided into two parts: the N-terminal globular head region made by amino acids 1-847, and the C-terminal rod region made by amino acids 848-1935 [4]
Patients We retrospectively reviewed patients with muscular disorders from Peking University First Hospital, and recruited patients suspected of Laing distal myopathy
Summary
Laing distal myopathy is a rare autosomal dominant inherited distal myopathy caused by mutations of the MYH7 gene affecting mainly the rod region. We described the clinical features, muscle MRI and pathological changes as well as genetic mutations in a group of Chinese patients with Laing distal myopathy. Slow/β-cardiac MyHC can be divided into two parts: the N-terminal globular head region made by amino acids 1-847, and the C-terminal rod region made by amino acids 848-1935 [4]. A variety of both cardiac and skeletal muscle disorders can be caused by MYH7 mutations. Mutations affecting the globular head region mainly cause cardiomyopathies, including familial hypertrophic/dilated cardiomyopathy, and left ventricular noncompaction (LVNC) cardiomyopathy, while mutations affecting the rod region mainly cause skeletal myopathies, including myosin storage myopathy (MSM), Laing distal myopathy (LDM) [5]
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