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Chan TYC, Hung LY, Lam TYL, Sheng B, Leung FYK, Lee HHC. SCN4A-related congenital myopathy in a Han Chinese patient: A case report and literature review. Heliyon 2024; 10:e23663. [PMID: 38187266 PMCID: PMC10770507 DOI: 10.1016/j.heliyon.2023.e23663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 11/23/2023] [Accepted: 12/09/2023] [Indexed: 01/09/2024] Open
Abstract
SCN4A mutations have been shown to be associated with myotonia, paramyotonia congenita, and periodic paralyses. More recently, loss-of-function variants in the SCN4A gene were also noted to be associated with rarer, autosomal recessive forms of congenital myasthenic syndrome and congenital myopathy. Diagnosis is challenging as the initial clinical presentation and histological features on muscle biopsies are non-specific. We report a Han Chinese patient presented with congenital myopathy with two missense SCN4A variants. The patient had an antenatal history of reduced fetal movements, polyhydramnios and a very preterm birth. At birth, she was noted to have low Apgar score, respiratory distress syndrome and hypotonia. Delayed motor development was noted in early childhood. Dysmorphic features such as an elongated face, dolichocephaly and high arched palate were present. At 16 years of age, the patient developed progressive muscle weakness and was wheelchair-bound by age 20. Muscle biopsy revealed non-specific changes only. Targeted hereditary myopathy panel testing by next generation sequencing revealed two previously unreported missense variants c.1841A > T p.(Asn614Ile) and c.4420G > A p.(Ala1474Thr) in the SCN4A gene. The clinical features of SCN4A-related congenital myopathy and myasthenic syndrome were reviewed. This case exemplifies the utility of next generation sequencing in the diagnosis of undifferentiated muscle disease.
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Affiliation(s)
- Tina Yee-Ching Chan
- Kowloon West Cluster Laboratory Genetic Service, Chemical Pathology Laboratory, Department of Pathology, Princess Margaret Hospital, Hong Kong Special Administrative Region
| | - Ling-Yin Hung
- Kowloon West Cluster Laboratory Genetic Service, Chemical Pathology Laboratory, Department of Pathology, Princess Margaret Hospital, Hong Kong Special Administrative Region
| | - Tiffany Yan-Lok Lam
- Department of Medicine and Geriatrics, Princess Margaret Hospital, Hong Kong Special Administrative Region
| | - Bun Sheng
- Department of Medicine and Geriatrics, Princess Margaret Hospital, Hong Kong Special Administrative Region
| | - Frank Ying-Kit Leung
- Kowloon West Cluster Laboratory Genetic Service, Chemical Pathology Laboratory, Department of Pathology, Princess Margaret Hospital, Hong Kong Special Administrative Region
- Department of Pathology, Yan Chai Hospital, Hong Kong Special Administrative Region
| | - Hencher Han-Chih Lee
- Kowloon West Cluster Laboratory Genetic Service, Chemical Pathology Laboratory, Department of Pathology, Princess Margaret Hospital, Hong Kong Special Administrative Region
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Lee HCH, Wong S, Sheng B, Pan NYK, Leung YKF, Lau KKD, Cheng YS, Ho LC, Li R, Lee CN, Tsoi TH, Cheung YFN, Fu YPM, Kan NCA, Chu YP, Au WCL, Yeung HMJ, Li SH, Cheung CFM, Tong HF, Hung LYE, Chan TYC, Li CT, Tong TYT, Tong TWC, Leung HYC, Lee KH, Yeung SYS, Lee SYB, Lau TCG, Lam CW, Mak CM, Chan AYW. Clinical and pathological characterization of FLNC-related myofibrillar myopathy caused by founder variant c.8129G>A in Hong Kong Chinese. Clin Genet 2020; 97:747-757. [PMID: 32022900 DOI: 10.1111/cge.13715] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 01/17/2020] [Accepted: 01/28/2020] [Indexed: 12/18/2022]
Abstract
FLNC-related myofibrillar myopathy could manifest as autosomal dominant late-onset slowly progressive proximal muscle weakness; involvements of cardiac and/or respiratory functions are common. We describe 34 patients in nine families of FLNC-related myofibrillar myopathy in Hong Kong ethnic Chinese diagnosed over the last 12 years, in whom the same pathogenic variant c.8129G>A (p.Trp2710*) was detected. Twenty-six patients were symptomatic when diagnosed; four patients died of pneumonia and/or respiratory failure. Abnormal amorphous material or granulofilamentous masses were detected in half of the cases, with mitochondrial abnormalities noted in two-thirds. We also show by haplotype analysis the founder effect associated with this Hong Kong variant, which might have occurred 42 to 71 generations ago or around Tang and Song dynasties, and underlain a higher incidence of myofibrillar myopathy among Hong Kong Chinese. The late-onset nature and slowly progressive course of the highly penetrant condition could have significant impact on the family members, and an early diagnosis could benefit the whole family. Considering another neighboring founder variant in FLNC in German patients, we advocate development of specific therapies such as chaperone-based or antisense oligonucleotide strategies for this particular type of myopathy.
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Affiliation(s)
| | - Shun Wong
- Department of Pathology, Princess Margaret Hospital, Hong Kong.,Pathology Department, St. Paul's Hospital, Hong Kong
| | - Bun Sheng
- Department of Medicine and Geriatrics, Princess Margaret Hospital, Hong Kong
| | - Nin-Yuan Keith Pan
- Department of Diagnostic Radiology, Princess Margaret Hospital, Hong Kong
| | | | | | - Yue Sandy Cheng
- Department of Clinical Pathology, Pamela Youde Nethersole Eastern Hospital, Hong Kong.,Department of Clinical Laboratory, Gleneagles Hong Kong Hospital, Hong Kong
| | - Luen-Cheung Ho
- Department of Pathology, Queen Elizabeth Hospital, Hong Kong
| | - Richard Li
- Department of Medicine, Pamela Youde Nethersole Eastern Hospital, Hong Kong
| | - Chi-Nam Lee
- Department of Medicine, Pamela Youde Nethersole Eastern Hospital, Hong Kong
| | - Tak-Hong Tsoi
- Department of Medicine, Pamela Youde Nethersole Eastern Hospital, Hong Kong
| | | | | | | | - Yim-Pui Chu
- Department of Medicine and Geriatrics, Princess Margaret Hospital, Hong Kong
| | - Wing-Chi Lisa Au
- Department of Medicine and Therapeutics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
| | | | - Siu-Hung Li
- Department of Medicine, North District Hospital, Hong Kong
| | | | - Hok-Fung Tong
- Department of Pathology, Princess Margaret Hospital, Hong Kong
| | | | | | - Chi Terence Li
- Department of Pathology, Princess Margaret Hospital, Hong Kong
| | | | | | | | - Ka-Ho Lee
- Department of Pathology, Princess Margaret Hospital, Hong Kong
| | | | | | | | - Ching-Wan Lam
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Chloe Miu Mak
- Department of Pathology, Princess Margaret Hospital, Hong Kong
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Abstract
Genetic testing has an increasingly important role in the diagnosis and management of cardiac disorders, where it confirms the diagnosis, aids prognostication and risk stratification and guides treatment. A genetic diagnosis in the proband also enables clarification of the risk for family members by cascade testing. Genetics in cardiac disorders is complex where epigenetic and environmental factors might come into interplay. Incomplete penetrance and variable expressivity is also common. Genetic results in cardiac conditions are mostly probabilistic and should be interpreted with all available clinical information. With this complexity in cardiac genetics, testing is only indicated in patients with a strong suspicion of an inheritable cardiac disorder after a full clinical evaluation. In this review we discuss the genetics underlying the major cardiomyopathies and channelopathies, and the practical aspects of diagnosing these conditions in the laboratory.
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