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Jiao K, Cheng N, Huan X, Zhang J, Ding Y, Luan X, Liu L, Wang X, Zhu B, Du K, Fan J, Gao M, Xia X, Wang N, Wang T, Xi J, Luo S, Lu J, Zhao C, Yue D, Zhu W. Pseudoexon activation by deep intronic variation in GNE myopathy with thrombocytopenia. Muscle Nerve 2024. [PMID: 38558464 DOI: 10.1002/mus.28092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 03/07/2024] [Accepted: 03/16/2024] [Indexed: 04/04/2024]
Abstract
INTRODUCTION/AIMS GNE myopathy is a rare autosomal recessive disorder caused by pathogenic variants in the GNE gene, which is essential for the sialic acid biosynthesis pathway. Although over 300 GNE variants have been reported, some patients remain undiagnosed with monoallelic pathogenic variants. This study aims to analyze the entire GNE genomic region to identify novel pathogenic variants. METHODS Patients with clinically compatible GNE myopathy and monoallelic pathogenic variants in the GNE gene were enrolled. The other GNE pathogenic variant was verified using comprehensive methods including exon 2 quantitative polymerase chain reaction and nanopore long-read single-molecule sequencing (LRS). RESULTS A deep intronic GNE variant, c.862+870C>T, was identified in nine patients from eight unrelated families. This variant generates a cryptic splice site, resulting in the activation of a novel pseudoexon between exons 5 and 6. It results in the insertion of an extra 146 nucleotides into the messengerRNA (mRNA), which is predicted to result in a truncated humanGNE1(hGNE1) protein. Peanut agglutinin(PNA) lectin staining of muscle tissues showed reduced sialylation of mucin O-glycans on sarcolemmal glycoproteins. Notably, a third of patients with the c.862+870C>T variant exhibited thrombocytopenia. A common core haplotype harboring the deep intronic GNE variant was found in all these patients. DISCUSSION The transcript with pseudoexon activation potentially affects sialic acid biosynthesis via nonsense-mediated mRNA decay, or resulting in a truncated hGNE1 protein, which interferes with normal enzyme function. LRS is expected to be more frequently incorporated in genetic analysis given its efficacy in detecting hard-to-find pathogenic variants.
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Affiliation(s)
- Kexin Jiao
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Nachuan Cheng
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Xiao Huan
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Jialong Zhang
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Yu Ding
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China
| | - Xinghua Luan
- Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - LingChun Liu
- The First People's Hospital of Yunnan Province, Kunming, China
| | - Xilu Wang
- Ministry of Education Key Laboratory of Contemporary Anthropology, Department of Anthropology and Human Genetics, School of Life Sciences, Fudan University, Shanghai, China
| | - Bochen Zhu
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Kunzhao Du
- Jinshan Hospital Center for Neurosurgery, Jinshan Hospital, Institute for Translational Brain Research, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Jiale Fan
- The State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, The Institutes of Brain Science, Shanghai, China
| | - Mingshi Gao
- Department of Pathology, Huashan Hospital, Fudan University, Shanghai, China
| | - Xingyu Xia
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Ningning Wang
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Tao Wang
- Department of Anesthesiology, Zhongshan Hospital, Institute for Translational Brain Research, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Jianying Xi
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Sushan Luo
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Jiahong Lu
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Chongbo Zhao
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
| | - Dongyue Yue
- Department of Neurology, Jing'an District Center Hospital of Shanghai, Shanghai, China
| | - Wenhua Zhu
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
- Huashan Rare Disease Center, Shanghai Medical College, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders (NCND), Shanghai, China
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