Complex sarcolemmal invaginations mimicking myotendinous junctions in a case of Laing early‐onset distal myopathy

et al. 2020

Preprint

Background: 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. Results: Six 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. Conclusions: Our 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.

Section: Discussionsupporting

confidence: 91%

Clinical features and genotypes of Laing distal myopathy in a group of Chinese patients, with in-frame deletions of MYH7 as common mutations

et al. 2020

Preprint

“…Muscle pathological changes in our patients including type 2 ber predominance, multi-cores and abnormal mitochondria, were relatively moderate and non-speci c, but were in accordance with previous researches [8,9,16,22]. Multi-cores on muscle biopsy of patient 6 were also reported in some previous articles in patients with the same MYH7 mutation p.E1508del [15,23,24]. This could be a speci c pathological feature of this genotype.…”

Section: Discussionsupporting

confidence: 91%

“…Referring to published articles on Laing distal myopathy, common mutation types also include missense mutations, and inframe indels. The p.K1617del and p.E1508del have also been reported in a few studies [5,6,8,9,12,15,19,23,24].Besides these in-frame indels in our study, other reported mutations include p.E1687del, p.K1729del, p.E1669del, p.K1729dup, p.L1793del, p.K1784del [5,9,11,16,[26][27][28]. Therefore, in-frame deletions or duplications are common types of mutations in Laing distal myopathy.…”

Section: Discussionsupporting

confidence: 83%

Clinical Features and Genotypes of Laing Distal Myopathy in a Group of Chinese Patients, With In-Frame Deletions of MYH7 as Common Mutations

et al. 2020

Preprint

Abstract Background: 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 of Laing distal myopathy. Results: Six patients with the confirmed diagnoses of Laing distal myopathy were recruited. Ankle dorsiflexion and finger extension weakness were common in our patients as well as neck flexion weakness. 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 severity of the disease. In-frame deletions of the MYH7 gene made up 3/4 of mutations in our patients, suggesting these are common mutations of Laing distal myopathy. Conclusions: Our study further expanded the phenotypes and genotypes of Laing distal myopathy. In-frame deletions of MYH7 gene are common causes of Laing distal myopathy.

“…Muscle pathological changes in our patients including type 2 fiber predominance, multi-cores and abnormal mitochondria, were relatively moderate and non-specific, which were in accordance with previous researches [8,9,17,23]. Multi-cores were seen on muscle biopsy of patient II-2 (family D), and were also reported in some previous articles in patients with the same MYH7 mutation p.E1508del [16,24,25]. This could be a specific pathological feature of this genotype.…”

Section: Discussionsupporting

confidence: 91%

Clinical features and genotypes of Laing distal myopathy in a group of Chinese patients, with in-frame deletions of MYH7 as common mutations

et al. 2020

Orphanet J Rare Dis

Background 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. Results Six 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. Conclusions Our 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.