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Huyghebaert J, Mateiu L, Elinck E, Van Rossem KE, Christiaenssen B, D'Incal CP, McCormack MK, Lazzarini A, Vandeweyer G, Kooy RF. Identification of a DLG3 stop mutation in the MRX20 family. Eur J Hum Genet 2024; 32:317-323. [PMID: 38273165 PMCID: PMC10923781 DOI: 10.1038/s41431-024-01537-7] [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: 06/30/2023] [Revised: 12/22/2023] [Accepted: 01/09/2024] [Indexed: 01/27/2024] Open
Abstract
Here, we identified the causal mutation in the MRX20 family, one of the larger X-linked pedigrees that have been described in which no gene had been identified up till now. In 1995, the putative disease gene had been mapped to the pericentromeric region on the X chromosome, but no follow-up studies were performed. Here, whole exome sequencing (WES) on two affected and one unaffected family member revealed the c.195del/p.(Thr66ProfsTer55) mutation in the DLG3 gene (NM_021120.4) that segregated with the affected individuals in the family. DLG3 mutations have been consequently associated with intellectual disability and are a plausible explanation for the clinical abnormalities observed in this family. In addition, we identified two other variants co-segregating with the phenotype: a stop gain mutation in SSX1 (c.358G>T/p.(Glu120Ter)) (NM_001278691.2) and a nonsynonymous SNV in USP27X (c.56 A>G/p.(Gln19Arg)) (NM_001145073.3). RNA sequencing revealed 14 differentially expressed genes (p value < 0.1) in 7 affected males compared to 4 unaffected males of the family, including four genes known to be associated with neurological disorders. Thus, in this paper we identified the c.195del/p.(Thr66ProfsTer55) mutation in the DLG3 gene (NM_021120.4) as likely responsible for the phenotype observed in the MRX20 family.
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Affiliation(s)
| | - Ligia Mateiu
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium
| | - Ellen Elinck
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium
| | | | | | | | - Michael K McCormack
- Department of Psychiatry, Rutgers University-Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
- Department of Cell Biology and Neurosciences, Virtua Health College of Medicine and Life Sciences of Rowan University, Stratford, NJ, 08084, USA
| | - Alice Lazzarini
- Department of Neurology, Rutgers University-Robert Wood Johnson Medical School, New Brunswick, NJ, 08903, USA
| | - Geert Vandeweyer
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium
| | - R Frank Kooy
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
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Meyer AP, Ma J, Brock G, Hashimoto S, Cottrell CE, Mathew M, Hunter JM, Leung ML, Corsmeier D, Jayaraman V, Waldrop MA, Flanigan KM. Exome sequencing in the pediatric neuromuscular clinic leads to more frequent diagnosis of both neuromuscular and neurodevelopmental conditions. Muscle Nerve 2023; 68:833-840. [PMID: 37789688 DOI: 10.1002/mus.27976] [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: 01/06/2023] [Revised: 09/06/2023] [Accepted: 09/10/2023] [Indexed: 10/05/2023]
Abstract
INTRODUCTION/AIMS Exome sequencing (ES) has proven to be a valuable diagnostic tool for neuromuscular disorders, which often pose a diagnostic challenge. The aims of this study were to investigate the clinical outcomes associated with utilization of ES in the pediatric neuromuscular clinic and to determine if specific phenotypic features or abnormal neurodiagnostic tests were predictive of a diagnostic result. METHODS This was a retrospective medical record review of 76 pediatric neuromuscular clinic patients who underwent ES. Based upon clinical assessment prior to ES, patients were divided into two groups: affected by neuromuscular (n = 53) or non-neuromuscular (n = 23) syndromes. RESULTS A diagnosis was made in 28/76 (36.8%), with 29 unique disorders identified. In the neuromuscular group, a neuromuscular condition was confirmed in 78% of those receiving a genetic diagnosis. Early age of symptom onset was associated with a significantly higher diagnostic yield. The most common reason neuromuscular diagnoses were not detected on prior testing was due to causative genes not being present on disease-specific panels. Changes to medical care were made in 57% of individuals receiving a diagnosis on ES. DISCUSSION These data further support ES as a powerful diagnostic tool in the pediatric neuromuscular clinic and highlight the advantages of ES over gene panels, including the ability to identify diagnoses regardless of etiology, identify genes newly associated with disease, and identify multiple confounding diagnoses. Rapid and accurate diagnosis by ES can not only end the patient's diagnostic odyssey, but often impacts patients' medical management and genetic counseling of families.
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Affiliation(s)
- Alayne P Meyer
- Division of Genetic and Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Jianing Ma
- Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio, USA
| | - Guy Brock
- Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio, USA
| | - Sayaka Hashimoto
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Catherine E Cottrell
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Pathology, The Ohio State University, Columbus, Ohio, USA
| | - Mariam Mathew
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Pathology, The Ohio State University, Columbus, Ohio, USA
| | - Jesse M Hunter
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Pathology, The Ohio State University, Columbus, Ohio, USA
| | - Marco L Leung
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Pathology, The Ohio State University, Columbus, Ohio, USA
| | - Don Corsmeier
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Vijayakumar Jayaraman
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Megan A Waldrop
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
- Department of Neurology, Nationwide Children's Hospital & The Ohio State University, Columbus, Ohio, USA
- Center for Gene Therapy, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Kevin M Flanigan
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
- Department of Neurology, Nationwide Children's Hospital & The Ohio State University, Columbus, Ohio, USA
- Center for Gene Therapy, Nationwide Children's Hospital, Columbus, Ohio, USA
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Spedicati B, Morgan A, Pianigiani G, Musante L, Rubinato E, Santin A, Nardone GG, Faletra F, Girotto G. Challenging Occam’s Razor: Dual Molecular Diagnoses Explain Entangled Clinical Pictures. Genes (Basel) 2022; 13:genes13112023. [PMID: 36360260 PMCID: PMC9690221 DOI: 10.3390/genes13112023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 10/31/2022] [Accepted: 11/01/2022] [Indexed: 11/06/2022] Open
Abstract
Dual molecular diagnoses are defined as the presence of pathogenic variants at two distinct and independently segregating loci that cause two different Mendelian conditions. In this study, we report the identification of double genetic disorders in a series of patients with complex clinical features. In the last 24 months, 342 syndromic patients have been recruited and clinically characterised. Whole Exome Sequencing analysis has been performed on the proband and on both parents and identified seven patients affected by a dual molecular diagnosis. Upon a detailed evaluation of both their clinical and molecular features, subjects are able to be divided into two groups: (A) five patients who present distinct phenotypes, due to each of the two different underlying genetic diseases; (B) two patients with overlapping clinical features that may be underpinned by both the identified genetic variations. Notably, only in one case a multilocus genomic variation was already suspected during the clinical evaluation. Overall, our findings highlight how dual molecular diagnoses represent a challenging model of complex inheritance that should always be considered whenever a patient shows atypical clinical features. Indeed, an accurate genetic characterisation is of the utmost importance to provide patients with a personalised and safe clinical management.
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Affiliation(s)
- Beatrice Spedicati
- Department of Medicine, Surgery and Health Sciences, University of Trieste, 34149 Trieste, Italy
| | - Anna Morgan
- Institute for Maternal and Child Health-I.R.C.C.S. “Burlo Garofolo”, 34137 Trieste, Italy
| | - Giulia Pianigiani
- Institute for Maternal and Child Health-I.R.C.C.S. “Burlo Garofolo”, 34137 Trieste, Italy
- Correspondence: ; Tel.: +39-040-3785539
| | - Luciana Musante
- Institute for Maternal and Child Health-I.R.C.C.S. “Burlo Garofolo”, 34137 Trieste, Italy
| | - Elisa Rubinato
- Institute for Maternal and Child Health-I.R.C.C.S. “Burlo Garofolo”, 34137 Trieste, Italy
| | - Aurora Santin
- Department of Medicine, Surgery and Health Sciences, University of Trieste, 34149 Trieste, Italy
| | | | - Flavio Faletra
- Institute for Maternal and Child Health-I.R.C.C.S. “Burlo Garofolo”, 34137 Trieste, Italy
| | - Giorgia Girotto
- Department of Medicine, Surgery and Health Sciences, University of Trieste, 34149 Trieste, Italy
- Institute for Maternal and Child Health-I.R.C.C.S. “Burlo Garofolo”, 34137 Trieste, Italy
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Methods to Improve Molecular Diagnosis in Genomic Cold Cases in Pediatric Neurology. Genes (Basel) 2022; 13:genes13020333. [PMID: 35205378 PMCID: PMC8871714 DOI: 10.3390/genes13020333] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 02/06/2022] [Accepted: 02/07/2022] [Indexed: 02/04/2023] Open
Abstract
During the last decade, genetic testing has emerged as an important etiological diagnostic tool for Mendelian diseases, including pediatric neurological conditions. A genetic diagnosis has a considerable impact on disease management and treatment; however, many cases remain undiagnosed after applying standard diagnostic sequencing techniques. This review discusses various methods to improve the molecular diagnostic rates in these genomic cold cases. We discuss extended analysis methods to consider, non-Mendelian inheritance models, mosaicism, dual/multiple diagnoses, periodic re-analysis, artificial intelligence tools, and deep phenotyping, in addition to integrating various omics methods to improve variant prioritization. Last, novel genomic technologies, including long-read sequencing, artificial long-read sequencing, and optical genome mapping are discussed. In conclusion, a more comprehensive molecular analysis and a timely re-analysis of unsolved cases are imperative to improve diagnostic rates. In addition, our current understanding of the human genome is still limited due to restrictions in technologies. Novel technologies are now available that improve upon some of these limitations and can capture all human genomic variation more accurately. Last, we recommend a more routine implementation of high molecular weight DNA extraction methods that is coherent with the ability to use and/or optimally benefit from these novel genomic methods.
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