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Hosseinpour S, Razmara E, Heidari M, Rezaei Z, Ashrafi MR, Dehnavi AZ, Kameli R, Bereshneh AH, Vahidnezhad H, Azizimalamiri R, Zamani Z, Pak N, Rasulinezhad M, Mohammadi B, Ghabeli H, Ghafouri M, Mohammadi M, Zamani GR, Badv RS, Saket S, Rabbani B, Mahdieh N, Ahani A, Garshasbi M, Tavasoli AR. A comprehensive study of mutation and phenotypic heterogeneity of childhood mitochondrial leukodystrophies. Brain Dev 2024; 46:167-179. [PMID: 38129218 DOI: 10.1016/j.braindev.2023.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 12/10/2023] [Accepted: 12/12/2023] [Indexed: 12/23/2023]
Abstract
OBJECTIVE Mitochondrial leukodystrophies (MLs) are mainly caused by impairments of the mitochondrial respiratory chains. This study reports the mutation and phenotypic spectrum of a cohort of 41 pediatric patients from 39 distinct families with MLs among 320 patients with a molecular diagnosis of leukodystrophies. METHODS This study summarizes the clinical, imaging, and molecular data of these patients for five years. RESULTS The three most common symptoms were neurologic regression (58.5%), pyramidal signs (58.5%), and extrapyramidal signs (43.9%). Because nuclear DNA mutations are responsible for a high percentage of pediatric MLs, whole exome sequencing was performed on all patients. In total, 39 homozygous variants were detected. Additionally, two previously reported mtDNA variants were identified with different levels of heteroplasmy in two patients. Among 41 mutant alleles, 33 (80.4%) were missense, 4 (9.8%) were frameshift (including 3 deletions and one duplication), and 4 (9.8%) were splicing mutations. Oxidative phosphorylation in 27 cases (65.8%) and mtDNA maintenance pathways in 8 patients (19.5%) were the most commonly affected mitochondrial pathways. In total, 5 novel variants in PDSS1, NDUFB9, FXBL4, SURF1, and NDUSF1 were also detected. In silico analyses showed how each novel variant may contribute to ML pathogenesis. CONCLUSIONS The findings of this study suggest whole-exome sequencing as a strong diagnostic genetic tool to identify the causative variants in pediatric MLs. In comparison between oxidative phosphorylation (OXPHOS) and mtDNA maintenance groups, brain stem and periaqueductal gray matter (PAGM) involvement were more commonly seen in OXPHOS group (P value of 0.002 and 0.009, respectively), and thinning of corpus callosum was observed more frequently in mtDNA maintenance group (P value of 0.042).
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Affiliation(s)
- Sareh Hosseinpour
- Department of Pediatric Neurology, Vali-e-Asr Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Ehsan Razmara
- Australian Regenerative Medicine Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Morteza Heidari
- Myelin Disorders Clinic, Division of Pediatric Neurology, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Zahra Rezaei
- Myelin Disorders Clinic, Division of Pediatric Neurology, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Mahmoud Reza Ashrafi
- Myelin Disorders Clinic, Division of Pediatric Neurology, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Ali Zare Dehnavi
- Myelin Disorders Clinic, Division of Pediatric Neurology, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran; Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, MN 55905, USA
| | - Reyhaneh Kameli
- Department of Cell and Molecular Biology & Microbiology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran
| | - Ali Hosseini Bereshneh
- Prenatal Diagnosis and Genetic Research Center, Dastgheib Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Hassan Vahidnezhad
- Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, USA; Department of Pediatrics, The University of Pennsylvania School of Medicine, Philadelphia, USA
| | - Reza Azizimalamiri
- Department of Pediatric Neurology, Golestan Medical, Educational, and Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Zahra Zamani
- MD, MPH, Community Medicine Specialist, Tehran University of Medical Sciences, Tehran, Iran
| | - Neda Pak
- Department of Radiology, Children's Hospital Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Maryam Rasulinezhad
- Myelin Disorders Clinic, Division of Pediatric Neurology, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Bahram Mohammadi
- Myelin Disorders Clinic, Division of Pediatric Neurology, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Homa Ghabeli
- Myelin Disorders Clinic, Division of Pediatric Neurology, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Ghafouri
- Myelin Disorders Clinic, Division of Pediatric Neurology, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Mahmoud Mohammadi
- Pediatric Neurology Division, Children's Medical Center, Pediatrics Center of Excellence, Tehran University of Medical Sciences, Tehran, Iran
| | - Gholam Reza Zamani
- Pediatric Neurology Division, Children's Medical Center, Pediatrics Center of Excellence, Tehran University of Medical Sciences, Tehran, Iran
| | - Reza Shervin Badv
- Pediatric Neurology Division, Children's Medical Center, Pediatrics Center of Excellence, Tehran University of Medical Sciences, Tehran, Iran
| | - Sasan Saket
- Iranian Child Neurology Center of Excellence, Pediatric Neurology Research Center, Research Institute for Children Health, Mofid Children's and Shohada-e Tajrish Hospitals, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Bahareh Rabbani
- Growth and Development Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Nejat Mahdieh
- Growth and Development Research Center, Tehran University of Medical Sciences, Tehran, Iran; Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Ali Ahani
- Mendel Medical Genetics Laboratory, Iran University of Medical Sciences, Tehran, Iran
| | - Masoud Garshasbi
- Department of Medical Genetics, Faculty of Medical Sciences, Jalal-Al Ahmad Hwy, Tarbiat Modares University, Tehran, Iran.
| | - Ali Reza Tavasoli
- Myelin Disorders Clinic, Division of Pediatric Neurology, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran; Neurology Division, Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ, USA.
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Tollefson MR, Gogal RA, Weaver AM, Schaefer AM, Marini RJ, Azaiez H, Kolbe DL, Wang D, Weaver AE, Casavant TL, Braun TA, Smith RJH, Schnieders MJ. Assessing variants of uncertain significance implicated in hearing loss using a comprehensive deafness proteome. Hum Genet 2023; 142:819-834. [PMID: 37086329 PMCID: PMC10182131 DOI: 10.1007/s00439-023-02559-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 04/11/2023] [Indexed: 04/23/2023]
Abstract
Hearing loss is the leading sensory deficit, affecting ~ 5% of the population. It exhibits remarkable heterogeneity across 223 genes with 6328 pathogenic missense variants, making deafness-specific expertise a prerequisite for ascribing phenotypic consequences to genetic variants. Deafness-implicated variants are curated in the Deafness Variation Database (DVD) after classification by a genetic hearing loss expert panel and thorough informatics pipeline. However, seventy percent of the 128,167 missense variants in the DVD are "variants of uncertain significance" (VUS) due to insufficient evidence for classification. Here, we use the deep learning protein prediction algorithm, AlphaFold2, to curate structures for all DVD genes. We refine these structures with global optimization and the AMOEBA force field and use DDGun3D to predict folding free energy differences (∆∆GFold) for all DVD missense variants. We find that 5772 VUSs have a large, destabilizing ∆∆GFold that is consistent with pathogenic variants. When also filtered for CADD scores (> 25.7), we determine 3456 VUSs are likely pathogenic at a probability of 99.0%. Of the 224 genes in the DVD, 166 genes (74%) exhibit one or more missense variants predicted to cause a pathogenic change in protein folding stability. The VUSs prioritized here affect 119 patients (~ 3% of cases) sequenced by the OtoSCOPE targeted panel. Approximately half of these patients previously received an inconclusive report, and reclassification of these VUSs as pathogenic provides a new genetic diagnosis for six patients.
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Affiliation(s)
- Mallory R Tollefson
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, 52242, USA
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology, University of Iowa Hospitals and Clinics, Iowa City, IA, 52242, USA
| | - Rose A Gogal
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, 52242, USA
| | - A Monique Weaver
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology, University of Iowa Hospitals and Clinics, Iowa City, IA, 52242, USA
| | - Amanda M Schaefer
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology, University of Iowa Hospitals and Clinics, Iowa City, IA, 52242, USA
| | - Robert J Marini
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology, University of Iowa Hospitals and Clinics, Iowa City, IA, 52242, USA
| | - Hela Azaiez
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology, University of Iowa Hospitals and Clinics, Iowa City, IA, 52242, USA
| | - Diana L Kolbe
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology, University of Iowa Hospitals and Clinics, Iowa City, IA, 52242, USA
| | - Donghong Wang
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology, University of Iowa Hospitals and Clinics, Iowa City, IA, 52242, USA
| | - Amy E Weaver
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology, University of Iowa Hospitals and Clinics, Iowa City, IA, 52242, USA
| | - Thomas L Casavant
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, 52242, USA
| | - Terry A Braun
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, 52242, USA
| | - Richard J H Smith
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology, University of Iowa Hospitals and Clinics, Iowa City, IA, 52242, USA.
| | - Michael J Schnieders
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, 52242, USA.
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA, 52242, USA.
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Tollefson MR, Gogal RA, Weaver AM, Schaefer AM, Marini RJ, Azaiez H, Kolbe DL, Wang D, Weaver AE, Casavant TL, Braun TA, Smith RJH, Schnieders M. Assessing Variants of Uncertain Significance Implicated in Hearing Loss Using a Comprehensive Deafness Proteome. RESEARCH SQUARE 2023:rs.3.rs-2508462. [PMID: 36778238 PMCID: PMC9915777 DOI: 10.21203/rs.3.rs-2508462/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Hearing loss is the leading sensory deficit, affecting ~ 5% of the population. It exhibits remarkable heterogeneity across 223 genes with 6,328 pathogenic missense variants, making deafness-specific expertise a prerequisite for ascribing phenotypic consequences to genetic variants. Deafness-implicated variants are curated in the Deafness Variation Database (DVD) after classification by a genetic hearing loss expert panel and thorough informatics pipeline. However, seventy percent of the 128,167 missense variants in the DVD are "variants of uncertain significance" (VUS) due to insufficient evidence for classification. Here, we use the deep learning protein prediction algorithm, AlphaFold2, to curate structures for all DVD genes. We refine these structures with global optimization and the AMOEBA force field and use DDGun3D to predict folding free energy differences (∆∆G Fold ) for all DVD missense variants. We find that 5,772 VUSs have a large, destabilizing ∆∆G Fold that is consistent with pathogenic variants. When also filtered for CADD scores (> 25.7), we determine 3,456 VUSs are likely pathogenic at a probability of 99.0%. These VUSs affect 119 patients (~ 3% of cases) sequenced by the OtoSCOPE targeted panel. Approximately half of these patients previously received an inconclusive report, and reclassification of these VUSs as pathogenic provides a new genetic diagnosis for six patients.
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Grochowska J, Czerwinska J, Borowski LS, Szczesny RJ. Mitochondrial RNA, a new trigger of the innate immune system. WILEY INTERDISCIPLINARY REVIEWS-RNA 2021; 13:e1690. [PMID: 34498404 DOI: 10.1002/wrna.1690] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 08/18/2021] [Accepted: 08/19/2021] [Indexed: 02/06/2023]
Abstract
Mitochondria play a pivotal role in numerous cellular processes. One of them is regulation of the innate immune pathway. In this instance, mitochondria function in two different aspects of regulatory mechanisms. First, mitochondria are part of the antiviral signaling cascade that is triggered in the cytoplasm and transmitted to effector proteins through mitochondria-localized proteins. Second, mitochondria can become an endogenous source of innate immune stimuli. Under some pathophysiological conditions, mitochondria release to the cytoplasm immunogenic factors, such as mitochondrial nucleic acids. Here, we focus on immunogenic mitochondrial double-stranded RNA (mt-dsRNA) and its origin and metabolism. We discuss factors that are responsible for regulating mt-dsRNA and its escape from mitochondria, emphasizing the contribution of polynucleotide phosphorylase (PNPase, PNPT1). Finally, we review current knowledge of the role of PNPase in human health and disease. This article is categorized under: RNA in Disease and Development > RNA in Disease.
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Affiliation(s)
- Joanna Grochowska
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Warsaw, Poland
| | - Jolanta Czerwinska
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Warsaw, Poland
| | - Lukasz S Borowski
- Faculty of Biology, Institute of Genetics and Biotechnology, University of Warsaw, Warsaw, Poland
| | - Roman J Szczesny
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Warsaw, Poland
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