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Almannai M, Marafi D, Zaki MS, Maroofian R, Efthymiou S, Saadi NW, Filimban B, Dafsari HS, Rahman F, Maqbool S, Faqeih E, Al Mutairi F, Alsharhan H, Abdelaty O, Bin-Hasan S, Duan R, Noureldeen MM, Alqattan A, Houlden H, Hunter JV, Posey JE, Lupski JR, El-Hattab AW. Expanding the phenotype of PPP1R21-related neurodevelopmental disorder. Clin Genet 2024; 105:620-629. [PMID: 38356149 PMCID: PMC11065596 DOI: 10.1111/cge.14492] [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: 12/20/2023] [Revised: 01/17/2024] [Accepted: 01/18/2024] [Indexed: 02/16/2024]
Abstract
PPP1R21 encodes for a conserved protein that is involved in endosomal maturation. Biallelic pathogenic variants in PPP1R21 have been associated with a syndromic neurodevelopmental disorder from studying 13 affected individuals. In this report, we present 11 additional individuals from nine unrelated families and their clinical, radiological, and molecular findings. We identified eight different variants in PPP1R21, of which six were novel variants. Global developmental delay and hypotonia are neurological features that were observed in all individuals. There is also a similar pattern of dysmorphic features with coarse faces as a gestalt observed in several individuals. Common findings in 75% of individuals with available brain imaging include delays in myelination, wavy outline of the bodies of the lateral ventricles, and slight prominence of the bodies of the lateral ventricles. PPP1R21-related neurodevelopmental disorder is associated with a consistent phenotype and should be considered in highly consanguineous individuals presenting with developmental delay/intellectual disability along with coarse facial features.
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Affiliation(s)
- Mohammed Almannai
- Genetics and Precision Medicine department (GPM), King
Abdullah Specialized Children’s Hospital (KASCH), King Abdulaziz Medical
City, Ministry of National Guard Health Affairs (MNG-HA), Riyadh, Saudi Arabia
- Medical Genomics Research Department, King Abdullah
International Medical Research Center, Ministry of National Guard Health Affairs,
King Saud Bin Abdulaziz University for Health Sciences, Ministry of National Guard
Health Affairs, Riyadh, Saudi Arabia
| | - Dana Marafi
- Department of Molecular and Human Genetics, Baylor College
of Medicine, Houston, Texas, 77030, USA
- Department of Pediatrics, College of Medicine, Kuwait
University, P.O. Box 24923, 13110 Safat, Kuwait
| | - Maha S. Zaki
- Clinical Genetics Department, Human Genetics and Genome
Research Institute National Research Centre, Cairo, Egypt
- Genetics Department, Armed Forces College of Medicine
(AFCM), Cairo, Egypt
| | - Reza Maroofian
- Department of Neuromuscular disorders, UCL Queen Square
Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Stephanie Efthymiou
- Department of Neuromuscular disorders, UCL Queen Square
Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Nebal Waill Saadi
- College of Medicine, University of Baghdad, Pediatric
Neurology, Children Welfare Teaching Hospital, Baghdad, Iraq
| | - Bilal Filimban
- Section of Medical Genetics, Children’s Hospital,
King Fahad Medical City, Riyadh, Saudi Arabia
| | - Hormos Salimi Dafsari
- Department of Pediatrics, Center for Rare Diseases,
Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne,
Germany
- Randall Centre for Cell and Molecular Biophysics,
Faculty of Life Sciences and Medicine (FoLSM), King’s College London, London,
United Kingdom
- Max-Planck-Institute for Biology of Ageing, Cologne,
Germany
- Cologne Excellence Cluster on Cellular Stress Responses
in Aging Associated Diseases (CECAD), Cologne, Germany
| | - Fatima Rahman
- Department of Developmental - Behavioral Pediatrics,
University of Child Health Sciences & The Children’s Hospital, Lahore,
Pakistan
| | - Shazia Maqbool
- Department of Developmental - Behavioral Pediatrics,
University of Child Health Sciences & The Children’s Hospital, Lahore,
Pakistan
| | - Eissa Faqeih
- Section of Medical Genetics, Children’s Hospital,
King Fahad Medical City, Riyadh, Saudi Arabia
| | - Fuad Al Mutairi
- Genetics and Precision Medicine department (GPM), King
Abdullah Specialized Children’s Hospital (KASCH), King Abdulaziz Medical
City, Ministry of National Guard Health Affairs (MNG-HA), Riyadh, Saudi Arabia
- Medical Genomics Research Department, King Abdullah
International Medical Research Center, Ministry of National Guard Health Affairs,
King Saud Bin Abdulaziz University for Health Sciences, Ministry of National Guard
Health Affairs, Riyadh, Saudi Arabia
| | - Hind Alsharhan
- Department of Pediatrics, College of Medicine, Kuwait
University, P.O. Box 24923, 13110 Safat, Kuwait
- Department of Pediatrics, Farwaniya Hospital, Ministry
of Health, Sabah Al-Nasser, 92426, Kuwait
- Kuwait Medical Genetics Center, Ministry of Health,
Sulaibikhat, 80901, Kuwait
- Department of Genetic Medicine, Johns Hopkins University
School of Medicine, Baltimore, MD, USA
| | - Omar Abdelaty
- Department of Pediatrics, Farwaniya Hospital, Ministry
of Health, Sabah Al-Nasser, 92426, Kuwait
| | - Saadoun Bin-Hasan
- Department of Pediatrics, Farwaniya Hospital, Ministry
of Health, Sabah Al-Nasser, 92426, Kuwait
| | - Ruizhi Duan
- Department of Molecular and Human Genetics, Baylor College
of Medicine, Houston, Texas, 77030, USA
| | - Mahmoud M. Noureldeen
- Department of Pediatrics, Faculty of Medicine, Beni-Suef
University, Beni-Suef, Egypt
| | - Alaa Alqattan
- Department of Pediatrics, Farwaniya Hospital, Ministry
of Health, Sabah Al-Nasser, 92426, Kuwait
| | - Henry Houlden
- Department of Neuromuscular disorders, UCL Queen Square
Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Jill V Hunter
- Texas Children Hospital, Houston, Texas, 77030,
USA
- Department of Radiology, Baylor College of Medicine,
Houston, Texas, 77030
| | - Jennifer E. Posey
- Department of Molecular and Human Genetics, Baylor College
of Medicine, Houston, Texas, 77030, USA
| | - James R. Lupski
- Department of Molecular and Human Genetics, Baylor College
of Medicine, Houston, Texas, 77030, USA
- Texas Children Hospital, Houston, Texas, 77030,
USA
- Human Genome Sequencing Center, Baylor College of
Medicine, Houston, Texas, 77030, USA
- Department of Pediatrics, Baylor College of Medicine,
Houston, Texas, 77030, USA
| | - Ayman W. El-Hattab
- Department of Clinical Sciences, College of Medicine,
University of Sharjah, Sharjah, United Arab Emirates
- Genetics Clinics, University Hospital Sharjah, Sharjah,
United Arab Emirates
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2
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Schuhmacher JS, Tom Dieck S, Christoforidis S, Landerer C, Davila Gallesio J, Hersemann L, Seifert S, Schäfer R, Giner A, Toth-Petroczy A, Kalaidzidis Y, Bohnsack KE, Bohnsack MT, Schuman EM, Zerial M. The Rab5 effector FERRY links early endosomes with mRNA localization. Mol Cell 2023; 83:1839-1855.e13. [PMID: 37267905 DOI: 10.1016/j.molcel.2023.05.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 12/06/2022] [Accepted: 05/08/2023] [Indexed: 06/04/2023]
Abstract
Localized translation is vital to polarized cells and requires precise and robust distribution of different mRNAs and ribosomes across the cell. However, the underlying molecular mechanisms are poorly understood and important players are lacking. Here, we discovered a Rab5 effector, the five-subunit endosomal Rab5 and RNA/ribosome intermediary (FERRY) complex, that recruits mRNAs and ribosomes to early endosomes through direct mRNA-interaction. FERRY displays preferential binding to certain groups of transcripts, including mRNAs encoding mitochondrial proteins. Deletion of FERRY subunits reduces the endosomal localization of transcripts in cells and has a significant impact on mRNA levels. Clinical studies show that genetic disruption of FERRY causes severe brain damage. We found that, in neurons, FERRY co-localizes with mRNA on early endosomes, and mRNA loaded FERRY-positive endosomes are in close proximity of mitochondria. FERRY thus transforms endosomes into mRNA carriers and plays a key role in regulating mRNA distribution and transport.
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Affiliation(s)
- Jan S Schuhmacher
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Susanne Tom Dieck
- Max Planck Institute for Brain Research, Max-von-Laue-Str. 4, 60438 Frankfurt am Main, Germany
| | - Savvas Christoforidis
- Biomedical Research Institute, Foundation for Research and Technology, 45110 Ioannina, Greece; Laboratory of Biological Chemistry, Department of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece
| | - Cedric Landerer
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany; Center for Systems Biology Dresden, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Jimena Davila Gallesio
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Lena Hersemann
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Sarah Seifert
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Ramona Schäfer
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Angelika Giner
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Agnes Toth-Petroczy
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany; Center for Systems Biology Dresden, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Yannis Kalaidzidis
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Katherine E Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Markus T Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, 37073 Göttingen, Germany; Göttingen Centre for Molecular Biosciences, University of Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany; Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany
| | - Erin M Schuman
- Max Planck Institute for Brain Research, Max-von-Laue-Str. 4, 60438 Frankfurt am Main, Germany
| | - Marino Zerial
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany; Center for Systems Biology Dresden, Pfotenhauerstrasse 108, 01307 Dresden, Germany.
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3
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Hentschel A, Meyer N, Kohlschmidt N, Groß C, Sickmann A, Schara-Schmidt U, Förster F, Töpf A, Christiansen J, Horvath R, Vorgerd M, Thompson R, Polavarapu K, Lochmüller H, Preusse C, Hannappel L, Schänzer A, Grüneboom A, Gangfuß A, Roos A. A Homozygous PPP1R21 Splice Variant Associated with Severe Developmental Delay, Absence of Speech, and Muscle Weakness Leads to Activated Proteasome Function. Mol Neurobiol 2023; 60:2602-2618. [PMID: 36692708 PMCID: PMC10039818 DOI: 10.1007/s12035-023-03219-9] [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: 08/03/2022] [Accepted: 01/04/2023] [Indexed: 01/25/2023]
Abstract
PPP1R21 acts as a co-factor for protein phosphatase 1 (PP1), an important serine/threonine phosphatase known to be essential for cell division, control of glycogen metabolism, protein synthesis, and muscle contractility. Bi-allelic pathogenic variants in PPP1R21 were linked to a neurodevelopmental disorder with hypotonia, facial dysmorphism, and brain abnormalities (NEDHFBA) with pediatric onset. Functional studies unraveled impaired vesicular transport as being part of PPP1R21-related pathomechanism. To decipher further the pathophysiological processes leading to the clinical manifestation of NEDHFBA, we investigated the proteomic signature of fibroblasts derived from the first NEDHFBA patient harboring a splice-site mutation in PPP1R21 and presenting with a milder phenotype. Proteomic findings and further functional studies demonstrate a profound activation of the ubiquitin-proteasome system with presence of protein aggregates and impact on cellular fitness and moreover suggest a cross-link between activation of the proteolytic system and cytoskeletal architecture (including filopodia) as exemplified on paradigmatic proteins including actin, thus extending the pathophysiological spectrum of the disease. In addition, the proteomic signature of PPP1R21-mutant fibroblasts displayed a dysregulation of a variety of proteins of neurological relevance. This includes increase proteins which might act toward antagonization of cellular stress burden in terms of pro-survival, a molecular finding which might accord with the presentation of a milder phenotype of our NEDHFBA patient.
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Affiliation(s)
- Andreas Hentschel
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V, Dortmund, Germany
| | - Nancy Meyer
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen, Germany
| | | | - Claudia Groß
- Institute of Clinical Genetics and Tumor Genetics, Bonn, Germany
| | - Albert Sickmann
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V, Dortmund, Germany
| | - Ulrike Schara-Schmidt
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen, Germany
| | - Fabian Förster
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen, Germany
| | - Ana Töpf
- The John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle Upon Tyne, UK
| | - Jon Christiansen
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen, Germany
| | - Rita Horvath
- Department of Clinical Neurosciences, John Van Geest Centre for Brain Repair, School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Matthias Vorgerd
- Department of Neurology, Heimer Institute for Muscle Research, University Hospital Bergmannsheil, Ruhr University Bochum, Bochum, Germany
| | - Rachel Thompson
- Children's Hospital of Eastern Ontario Research Institute; Division of Neurology, Department of Medicine, The Ottawa Hospital; and Brain and Mind Research Institute, University of Ottawa, Ottawa, Canada
| | - Kiran Polavarapu
- Children's Hospital of Eastern Ontario Research Institute; Division of Neurology, Department of Medicine, The Ottawa Hospital; and Brain and Mind Research Institute, University of Ottawa, Ottawa, Canada
| | - Hanns Lochmüller
- Children's Hospital of Eastern Ontario Research Institute; Division of Neurology, Department of Medicine, The Ottawa Hospital; and Brain and Mind Research Institute, University of Ottawa, Ottawa, Canada
| | - Corinna Preusse
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Luis Hannappel
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen, Germany
| | - Anne Schänzer
- Institute of Neuropathology, Justus Liebig University, Gießen, Germany
| | - Anika Grüneboom
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V, Dortmund, Germany
| | - Andrea Gangfuß
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen, Germany
| | - Andreas Roos
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen, Germany.
- Department of Neurology, Heimer Institute for Muscle Research, University Hospital Bergmannsheil, Ruhr University Bochum, Bochum, Germany.
- Children's Hospital of Eastern Ontario Research Institute; Division of Neurology, Department of Medicine, The Ottawa Hospital; and Brain and Mind Research Institute, University of Ottawa, Ottawa, Canada.
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4
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Vaneynde P, Verbinnen I, Janssens V. The role of serine/threonine phosphatases in human development: Evidence from congenital disorders. Front Cell Dev Biol 2022; 10:1030119. [PMID: 36313552 PMCID: PMC9608770 DOI: 10.3389/fcell.2022.1030119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 09/27/2022] [Indexed: 11/23/2022] Open
Abstract
Reversible protein phosphorylation is a fundamental regulation mechanism in eukaryotic cell and organismal physiology, and in human health and disease. Until recently, and unlike protein kinases, mutations in serine/threonine protein phosphatases (PSP) had not been commonly associated with disorders of human development. Here, we have summarized the current knowledge on congenital diseases caused by mutations, inherited or de novo, in one of 38 human PSP genes, encoding a monomeric phosphatase or a catalytic subunit of a multimeric phosphatase. In addition, we highlight similar pathogenic mutations in genes encoding a specific regulatory subunit of a multimeric PSP. Overall, we describe 19 affected genes, and find that most pathogenic variants are loss-of-function, with just a few examples of gain-of-function alterations. Moreover, despite their widespread tissue expression, the large majority of congenital PSP disorders are characterised by brain-specific abnormalities, suggesting a generalized, major role for PSPs in brain development and function. However, even if the pathogenic mechanisms are relatively well understood for a small number of PSP disorders, this knowledge is still incomplete for most of them, and the further identification of downstream targets and effectors of the affected PSPs is eagerly awaited through studies in appropriate in vitro and in vivo disease models. Such lacking studies could elucidate the exact mechanisms through which these diseases act, and possibly open up new therapeutic avenues.
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Affiliation(s)
- Pieter Vaneynde
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, University of Leuven (KU Leuven), Leuven, Belgium
- Leuven Brain Institute (LBI), Leuven, Belgium
| | - Iris Verbinnen
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, University of Leuven (KU Leuven), Leuven, Belgium
- Leuven Brain Institute (LBI), Leuven, Belgium
| | - Veerle Janssens
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, University of Leuven (KU Leuven), Leuven, Belgium
- Leuven Brain Institute (LBI), Leuven, Belgium
- *Correspondence: Veerle Janssens,
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Kotecha UH, Mistri M, Rayabarapu P, Shah P, Shah N. The diagnostic utility of exome-based carrier screening in families with a positive family history. Am J Med Genet A 2022; 188:1323-1333. [PMID: 34997808 DOI: 10.1002/ajmg.a.62633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 10/15/2021] [Accepted: 12/26/2021] [Indexed: 11/09/2022]
Abstract
Identification of disease-causing variants in families with a history of a suspected recessive disorder is essential for appropriate counseling and reproductive decision making. The present case series depicts the utility of whole exome-based phenotypes-driven carrier analysis in 14 families with a positive family history. A phenotype-based analysis revealed a putative diagnostic yield of 71.4%. Proband sample, though insufficient, was available in only one family, which allowed the diagnosis to be confirmed. In the remaining nine families, despite the detection of heterozygous pathogenic/likely pathogenic variants, only a putative diagnosis was possible due to incomplete proband phenotyping as well as nonavailability of proband samples. We describe the youngest known patient homozygous for a likely pathogenic variant in PPP1R21. He is currently asymptomatic at 7 days of life and has a simplified gyral pattern on neuroimaging. The case series, though small, captures the challenges in the diagnosis of genetic disorders in low to middle income countries with in-equitable health care access. It reinforces the significance of detailed phenotyping in the proband as well as the importance of DNA storage for a conclusive diagnosis. A recurring post-test counseling challenge was risk ascertainment and reproductive decision making in subsequent pregnancies if the detected pathogenic/likely pathogenic variants are co-inherited, in families with a putative diagnosis. When opted for, prenatal testing in such a scenario would be limited in its ability to comment on the fetal status with respect to the disorder in the proband.
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Affiliation(s)
| | - Mehul Mistri
- Neuberg Centre for Genomic Medicine, Ahmedabad, India
| | | | - Parth Shah
- Neuberg Centre for Genomic Medicine, Ahmedabad, India
| | - Nidhi Shah
- Neuberg Centre for Genomic Medicine, Ahmedabad, India
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Saleh S, Beyyumi E, Al Kaabi A, Hertecant J, Barakat D, Al Dhaheri NS, Al-Gazali L, Al Shamsi A. Spectrum of neuro-genetic disorders in the United Arab Emirates national population. Clin Genet 2021; 100:573-600. [PMID: 34374989 DOI: 10.1111/cge.14044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 07/31/2021] [Accepted: 08/06/2021] [Indexed: 11/27/2022]
Abstract
Clinical and molecular characterization of neuro-genetic disorders among UAE national patients seen in the Genetic Clinic at Tawam hospital over a period of 3 years. A retrospective chart review of all Emirati patients assessed by clinical geneticists due to neuro-genetic disorders including global developmental delay, ASD, ID, ADHD, and epilepsy in combination with abnormalities of other organ systems. Each patient had proper assessment including detailed history, three-generation family history, developmental history and detailed physical examination looking for other system involvement. Hearing test and ophthalmological examination were performed when needed. Magnetic resonance imaging (MRI) of the brain, echocardiogram, and renal ultrasound were pursued as indicated. Detailed psychological evaluation and psychometric assessment were done when indicated. The review was done for a period between January 2018 and December 2020. Genetic investigations included chromosome karyotype, FISH study, metabolic/biochemical tests, chromosome microarray, gene sequencing, targeted mutation testing, trio whole exome and trio genome sequencing. A total of 644 patients with developmental delay, ID, learning difficulty, ASD, ADHD, or NNDs, were seen in genetic clinic from January 2018 to December 2020. A total of 506 patients were included in this review, all completed the genetic evaluations during the study period. There were 398 (61.8%) males and 246 (38.2%) females, with a ratio of 1.6:1. Positive family history of NDD was documented in 132 families, while 115 families had negative history and family history was unknown/unclear in the remaining. Fifty seven (11.26% [57/506]) patients had positive microarray results. Hundred ninety seven (38.9% [197/506]) patients had positive molecular testing. Genetic disorders were found in 133 (67.5% [133/197]) and inborn errors of metabolism were found in 42 (21.3% [42/197]). Consanguinity was documented in 139 patients with positive molecular diagnoses (139/197, 70.5%). Sixty nine (35% [69/197]) patients had autosomal dominant disorders, majority were De Novo (84%). Ninety-five (48% [95/197]) patients had autosomal recessive diseases, 40 mutations involved inborn errors of metabolism and 50 mutations involved genetic disorders. Pathogenic variants causing both autosomal dominant and recessive disorders were found in 98 patients (49.7% [98/197]), likely pathogenic variants causing both autosomal dominant and recessive disorders were found in 66 patients (33.5% [66/197]). X-linked related disorders were found in 10 patients (5% [10/197]). Mitochondrial mutation was found in one patient. Novel mutations were found in 76 patients (76/197 i.e., 38.56%). Twenty two patients had variants of unknown significant. The remaining 252 studied patients (252/506 i.e., 49.8%), remained undiagnosed. This study shows that neuro-genetic disorders in the UAE are very heterogeneous at clinical and molecular levels. Using microarray, WES and WGS a diagnosis was reached in 50% of the patients while no diagnosis was reached in other half of the studied patients. It is possible that some mutations were missed by WGS and WES. However, it is also possible that many of disorders in UAE population are novel and the causative mutation is not yet discovered. More researches need to be done in this population to uncover the molecular basis of these disorders.
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Affiliation(s)
- Sirine Saleh
- Pediatrics Department, Tawam Hospital, Al Ain, United Arab Emirates
| | - Ela Beyyumi
- Pediatrics Department, Tawam Hospital, Al Ain, United Arab Emirates
| | - Aysha Al Kaabi
- Pediatrics Department, Tawam Hospital, Al Ain, United Arab Emirates
| | - Jozef Hertecant
- Genetic Division, Pediatrics Department, Tawam Hospital, Al Ain, United Arab Emirates
| | - Doaa Barakat
- Psychiatry Department, Behvioral Sciences Institute, Al Ain Hospital, Al Ain, United Arab Emirates
| | - Noura S Al Dhaheri
- Department of Pediatrics & Department of Genetics & Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Lihadh Al-Gazali
- Departments of Pediatrics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Aisha Al Shamsi
- Genetic Division, Pediatrics Department, Tawam Hospital, Al Ain, United Arab Emirates
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