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Geist Hauserman J, Laverty CG, Donkervoort S, Hu Y, Silverstein S, Neuhaus SB, Saade D, Vaughn G, Malicki D, Kaur R, Li Y, Luo Y, Liu P, Burr P, Foley AR, Mohassel P, Bönnemann CG. Clinical, immunohistochemical, and genetic characterization of splice-altering biallelic DES variants: Therapeutic implications. HGG ADVANCES 2024; 5:100274. [PMID: 38358893 PMCID: PMC10876619 DOI: 10.1016/j.xhgg.2024.100274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 01/24/2024] [Accepted: 01/24/2024] [Indexed: 02/17/2024] Open
Abstract
Pathogenic variants in the DES gene clinically manifest as progressive skeletal muscle weakness, cardiomyopathy with associated severe arrhythmias, and respiratory insufficiency, and are collectively known as desminopathies. While most DES pathogenic variants act via a dominant mechanism, recessively acting variants have also been reported. Currently, there are no effective therapeutic interventions for desminopathies of any type. Here, we report an affected individual with rapidly progressive dilated cardiomyopathy, requiring heart transplantation at age 13 years, in the setting of childhood-onset skeletal muscle weakness. We identified biallelic DES variants (c.640-13 T>A and c.1288+1 G>A) and show aberrant DES gene splicing in the affected individual's muscle. Through the generation of an inducible lentiviral system, we transdifferentiated fibroblast cultures derived from the affected individual into myoblasts and validated this system using RNA sequencing. We tested rationally designed, custom antisense oligonucleotides to screen for splice correction in these transdifferentiated cells and a functional minigene splicing assay. However, rather than correctly redirecting splicing, we found them to induce undesired exon skipping. Our results indicate that, while an individual precision-based molecular therapeutic approach to splice-altering pathogenic variants is promising, careful preclinical testing is imperative for each novel variant to test the feasibility of this type of approach for translation.
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Affiliation(s)
- Janelle Geist Hauserman
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA.
| | | | - Sandra Donkervoort
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
| | - Ying Hu
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
| | - Sarah Silverstein
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
| | - Sarah B Neuhaus
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
| | - Dimah Saade
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
| | | | | | - Rupleen Kaur
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
| | - Yuesheng Li
- DNA Sequencing and Genomics Core, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, USA
| | - Yan Luo
- DNA Sequencing and Genomics Core, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, USA
| | - Poching Liu
- DNA Sequencing and Genomics Core, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, USA
| | - Patrick Burr
- DNA Sequencing and Genomics Core, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, USA
| | - A Reghan Foley
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
| | - Payam Mohassel
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
| | - Carsten G Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA.
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2
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Kalyta K, Stelmaszczyk W, Szczęśniak D, Kotuła L, Dobosz P, Mroczek M. The Spectrum of the Heterozygous Effect in Biallelic Mendelian Diseases-The Symptomatic Heterozygote Issue. Genes (Basel) 2023; 14:1562. [PMID: 37628614 PMCID: PMC10454578 DOI: 10.3390/genes14081562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 07/26/2023] [Accepted: 07/27/2023] [Indexed: 08/27/2023] Open
Abstract
Heterozygous carriers of pathogenic/likely pathogenic variants in autosomal recessive disorders seem to be asymptomatic. However, in recent years, an increasing number of case reports have suggested that mild and unspecific symptoms can occur in some heterozygotes, as symptomatic heterozygotes have been identified across different disease types, including neurological, neuromuscular, hematological, and pulmonary diseases. The symptoms are usually milder in heterozygotes than in biallelic variants and occur "later in life". The status of symptomatic heterozygotes as separate entities is often disputed, and alternative diagnoses are considered. Indeed, often only a thin line exists between dual, dominant, and recessive modes of inheritance and symptomatic heterozygosity. Interestingly, recent population studies have found global disease effects in heterozygous carriers of some genetic variants. What makes the few heterozygotes symptomatic, while the majority show no symptoms? The molecular basis of this phenomenon is still unknown. Possible explanations include undiscovered deep-splicing variants, genetic and environmental modifiers, digenic/oligogenic inheritance, skewed methylation patterns, and mutational burden. Symptomatic heterozygotes are rarely reported in the literature, mainly because most did not undergo the complete diagnostic procedure, so alternative diagnoses could not be conclusively excluded. However, despite the increasing accessibility to high-throughput technologies, there still seems to be a small group of patients with mild symptoms and just one variant of autosomes in biallelic diseases. Here, we present some examples, the current state of knowledge, and possible explanations for this phenomenon, and thus argue against the existing dominant/recessive classification.
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Affiliation(s)
- Kateryna Kalyta
- School of Life Sciences, FHNW—University of Applied Sciences, 4132 Muttenz, Switzerland;
| | - Weronika Stelmaszczyk
- School of Cellular and Molecular Medicine, University of Bristol, Bristol BS8 1TD, UK;
| | - Dominika Szczęśniak
- Institute of Psychiatry and Neurology in Warsaw, Genetics Department, 02-957 Warsaw, Poland;
| | - Lidia Kotuła
- Department of Genetics, Medical University, 20-080 Lublin, Poland;
| | - Paula Dobosz
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5A, 02-106 Warsaw, Poland;
| | - Magdalena Mroczek
- University Hospital Basel, University of Basel, 4031 Basel, Switzerland
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D A, Y L, R S, H D, E B, Rm W, I V, L C, N.J D. Background splicing as a predictor of aberrant splicing in genetic disease. RNA Biol 2022; 19:256-265. [PMID: 35188075 PMCID: PMC8865296 DOI: 10.1080/15476286.2021.2024031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Mutations of splice sites, auxiliary splicing elements and the splicing machinery cause a wide range of genetic disease. Here we report that many of the complex effects of splicing mutations can be predicted from background splicing information, with emphasis on BRCA1, BRCA2 and DMD. Background splicing arises from very low level splicing between rarely used background splice sites and from low-level exon skipping between intron splice sites. We show how this information can be downloaded from the Snaptron database of spliced RNA, which we then compared with databases of human splice site mutations. We report that inactivating mutations of intron splice sites typically caused the non-mutated partner splice site to splice to a known background splice site in over 90% of cases and to the strongest background splice site in the large majority of cases. Consequently, background splicing information can usefully predict the effects of splice site mutations, which include cryptic splice activation and single or multiple exon skipping. In addition, de novo splice sites and splice sites involved in pseudoexon formation, recursive splicing and aberrant splicing in cancer show a 90% match to background splice sites, so establishing that the enhancement of background splicing causes a wide range of splicing aberrations. We also discuss how background splicing information can identify cryptic splice sites that might be usefully targeted by antisense oligonucleotides (ASOs) and how it might indicate possible multiple exon skipping side effects of ASOs designed to induce single exon skipping.
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Affiliation(s)
- Alexieva D
- Department of Metabolism, Digestion and Reproduction, Institute of Reproductive and Developmental Biology, Imperial College London, London, UK
| | - Long Y
- Department of Metabolism, Digestion and Reproduction, Institute of Reproductive and Developmental Biology, Imperial College London, London, UK
| | - Sarkar R
- Department of Metabolism, Digestion and Reproduction, Institute of Reproductive and Developmental Biology, Imperial College London, London, UK
| | - Dhayan H
- Department of Metabolism, Digestion and Reproduction, Institute of Reproductive and Developmental Biology, Imperial College London, London, UK
| | - Bruet E
- Department of Metabolism, Digestion and Reproduction, Institute of Reproductive and Developmental Biology, Imperial College London, London, UK
| | - Winston Rm
- Department of Metabolism, Digestion and Reproduction, Institute of Reproductive and Developmental Biology, Imperial College London, London, UK
| | - Vorechovsky I
- Faculty of Medicine, University of Southampton, Southampton, UK
| | - Castellano L
- Department of Surgery and Cancer, Imperial College London, Imperial Centre for Translational and Experimental Medicine (Ictem), London, UK
- School of Life Sciences, University of Sussex, Falmer, UK
| | - Dibb N.J
- Department of Metabolism, Digestion and Reproduction, Institute of Reproductive and Developmental Biology, Imperial College London, London, UK
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Macias A, Fichna JP, Topolewska M, Rȩdowicz MJ, Kaminska AM, Kostera-Pruszczyk A. Targeted Next-Generation Sequencing Reveals Mutations in Non-coding Regions and Potential Regulatory Sequences of Calpain-3 Gene in Polish Limb-Girdle Muscular Dystrophy Patients. Front Neurosci 2021; 15:692482. [PMID: 34720847 PMCID: PMC8551377 DOI: 10.3389/fnins.2021.692482] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 09/17/2021] [Indexed: 01/22/2023] Open
Abstract
Limb–girdle muscular dystrophy type R1 (LGMDR1) is caused by mutations in CAPN3 and is the most common type of recessive LGMD. Even with the use of whole-exome sequencing (WES), only one mutant allele of CAPN3 is found in a significant number of LGMDR patients. This points to a role of non-coding, intronic or regulatory, sequence variants in the disease pathogenesis. Targeted sequencing of the whole CAPN3 gene including not only intronic, 3′ and 5′ UTRs but also potential regulatory regions was performed in 27 patients suspected with LGMDR1. This group included 13 patients with only one mutated CAPN3 allele detected previously with exome sequencing. A second rare variant in the non-coding part of CAPN3 was found in 11 of 13 patients with previously identified single mutation. Intronic mutations were found in 10 cases, with c.1746-20C>G variant present in seven patients. In addition, a large deletion of exons 2–8 was found in one patient. In the patients with no causative mutation previously found, we detected rare CAPN3 variants in 5 out of 10 patients and in two of them in a compound heterozygous state. Rare variants within putative regulatory sequences distant from the CAPN3 gene were found in 15 patients, although in 11 of these cases, other variants are deemed causative. The results indicate that intronic mutations are common in Polish LGMDR patients, and testing for non-coding mutations in CAPN3 should be performed in apparently single heterozygous patients.
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Affiliation(s)
- Anna Macias
- Department of Neurology, Medical University of Warsaw, Warsaw, Poland
| | - Jakub Piotr Fichna
- Laboratory of Neurogenetics, Department of Neurodegenerative Disorders, Mossakowski Medical Research Institute, Polish Academy of Sciences, Warsaw, Poland
| | - Malgorzata Topolewska
- Laboratory of Molecular Basis of Cell Motility, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Maria J Rȩdowicz
- Laboratory of Molecular Basis of Cell Motility, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Anna M Kaminska
- Department of Neurology, Medical University of Warsaw, Warsaw, Poland
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Zhu F, Zhang F, Hu L, Liu H, Li Y. Integrated Genome and Transcriptome Sequencing to Solve a Neuromuscular Puzzle: Miyoshi Muscular Dystrophy and Early Onset Primary Dystonia in Siblings of the Same Family. Front Genet 2021; 12:672906. [PMID: 34276779 PMCID: PMC8283672 DOI: 10.3389/fgene.2021.672906] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/23/2021] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Neuromuscular disorders (NMD), many of which are hereditary, affect muscular function. Due to advances in high-throughput sequencing technologies, the diagnosis of hereditary NMDs has dramatically improved in recent years. METHODS AND RESULTS In this study, we report an family with two siblings exhibiting two different NMD, Miyoshi muscular dystrophy (MMD) and early onset primary dystonia (EOPD). Whole exome sequencing (WES) identified a novel monoallelic frameshift deletion mutation (dysferlin: c.4404delC/p.I1469Sfs∗17) in the Dysferlin gene in the index patient who suffered from MMD. This deletion was inherited from his unaffected father and was carried by his younger sister with EOPD. However, immunostaining staining revealed an absence of dysferlin expression in the proband's muscle tissue and thus suggested the presence of the second underlying mutant allele in dysferlin. Using integrated RNA sequencing (RNA-seq) and whole genome sequencing (WGS) of muscle tissue, a novel deep intronic mutation in dysferlin (dysferlin: c.5341-415A > G) was discovered in the index patient. This mutation caused aberrant mRNA splicing and inclusion of an additional pseudoexon (PE) which we termed PE48.1. This PE was inherited from his unaffected mother. PE48.1 inclusion altered the Dysferlin sequence, causing premature termination of translation. CONCLUSION Using integrated genome and transcriptome sequencing, we discovered hereditary MMD and EOPD affecting two siblings of same family. Our results added further weight to the combined use of RNA-seq and WGS as an important method for detection of deep intronic gene mutations, and suggest that integrated sequencing assays are an effective strategy for the diagnosis of hereditary NMDs.
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Affiliation(s)
- Feng Zhu
- Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Clinic Center of Human Gene Research, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Fengxiao Zhang
- Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Clinic Center of Human Gene Research, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Lizhi Hu
- Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Clinic Center of Human Gene Research, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Haowen Liu
- Department of Neurology, The Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Yahua Li
- Department of Respiratory Medicine, The Third Hospital of Hebei Medical University, Shijiazhuang, China
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Zhong H, Zheng Y, Zhao Z, Lin P, Xi J, Zhu W, Lin J, Lu J, Yu M, Zhang W, Lv H, Yan C, Hu J, Wang Z, Lu J, Zhao C, Yuan Y, Luo S. Molecular landscape of CAPN3 mutations in limb-girdle muscular dystrophy type R1: from a Chinese multicentre analysis to a worldwide perspective. J Med Genet 2020; 58:729-736. [PMID: 32994280 DOI: 10.1136/jmedgenet-2020-107159] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 07/31/2020] [Accepted: 08/14/2020] [Indexed: 01/29/2023]
Abstract
BACKGROUND Limb-girdle muscular dystrophy type R1 (LGMDR1) can be caused by recessive CAPN3 mutations accounting for the majority of LGMD. To date, no systemic evaluation has been performed to analyse the detrimental and normal mutations on CAPN3 and its hotspots. METHODS CAPN3 variants (n=112) from a total of 124 patients with LGMDR1 recruited in four centres in China were retrospectively analysed. Then external CAPN3 variants (n=2031) from online databases were integrated with our Chinese cohort data to achieve a worldwide perspective on CAPN3 mutations. According to their related phenotypes (LGMDR1 or normal), we analysed consequence, distribution, ethnicity and severity scores of CAPN3 mutations. RESULTS Two hotspot mutations were identified including c.2120A>G in Chinese population and c.550del in Europe. According to the integrated dataset, 521 mutations were classified as LGMDR1-related and converged on exons 1, 10, 5, 22 and 13 of CAPN3. The remaining 1585 variants were classified as normal-population related. The deleterious ratio of LGMDR1-relevant variants to total variants in each population was 0.26 on average with a maximum of 0.35 in Finns and a minimum of 0.21 in South Asians. Severity evaluation showed that Chinese LGMDR1-related variants exhibited a higher risk (Combined Annotation Dependent Depletion score +1.10) than that from database patients (p<0.001). CONCLUSIONS This study confirmed two hotspots and LGMDR1-related CAPN3 variants, highlighting the advantages in using a data-based comprehensive analysis to achieve a genetic landscape for patients with LGMDR1.
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Affiliation(s)
- Huahua Zhong
- Department of Neurology, Huashan Hospital Fudan University, Shanghai, China
| | - Yiming Zheng
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Zhe Zhao
- Department of Neuromuscular Disorders, Hebei Medical University Third Affiliated Hospital, Shijiazhuang, China
| | - Pengfei Lin
- Department of Neurology, Shandong University Qilu Hospital, Jinan, China
| | - Jianying Xi
- Department of Neurology, Huashan Hospital Fudan University, Shanghai, China
| | - Wenhua Zhu
- Department of Neurology, Huashan Hospital Fudan University, Shanghai, China
| | - Jie Lin
- Department of Neurology, Huashan Hospital Fudan University, Shanghai, China
| | - Jun Lu
- Department of Neurology, Huashan Hospital Fudan University, Shanghai, China
| | - Meng Yu
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Wei Zhang
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - He Lv
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Chuanzhu Yan
- Department of Neurology, Shandong University Qilu Hospital, Jinan, China
| | - Jing Hu
- Department of Neuromuscular Disorders, Hebei Medical University Third Affiliated Hospital, Shijiazhuang, China
| | - Zhaoxia Wang
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Jiahong Lu
- Department of Neurology, Huashan Hospital Fudan University, Shanghai, China
| | - Chongbo Zhao
- Department of Neurology, Huashan Hospital Fudan University, Shanghai, China
| | - Yun Yuan
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Sushan Luo
- Department of Neurology, Huashan Hospital Fudan University, Shanghai, China
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