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Mohammadian Gol T, Zahedipour F, Trosien P, Ureña-Bailén G, Kim M, Antony JS, Mezger M. Gene therapy in pediatrics - Clinical studies and approved drugs (as of 2023). Life Sci 2024; 348:122685. [PMID: 38710276 DOI: 10.1016/j.lfs.2024.122685] [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: 01/19/2024] [Revised: 04/17/2024] [Accepted: 05/03/2024] [Indexed: 05/08/2024]
Abstract
Gene therapy in pediatrics represents a cutting-edge therapeutic strategy for treating a range of genetic disorders that manifest in childhood. Gene therapy involves the modification or correction of a mutated gene or the introduction of a functional gene into a patient's cells. In general, it is implemented through two main modalities namely ex vivo gene therapy and in vivo gene therapy. Currently, a noteworthy array of gene therapy products has received valid market authorization, with several others in various stages of the approval process. Additionally, a multitude of clinical trials are actively underway, underscoring the dynamic progress within this field. Pediatric genetic disorders in the fields of hematology, oncology, vision and hearing loss, immunodeficiencies, neurological, and metabolic disorders are areas for gene therapy interventions. This review provides a comprehensive overview of the evolution and current progress of gene therapy-based treatments in the clinic for pediatric patients. It navigates the historical milestones of gene therapies, currently approved gene therapy products by the U.S. Food and Drug Administration (FDA) and/or European Medicines Agency (EMA) for children, and the promising future for genetic disorders. By providing a thorough compilation of approved gene therapy drugs and published results of completed or ongoing clinical trials, this review serves as a guide for pediatric clinicians to get a quick overview of the situation of clinical studies and approved gene therapy products as of 2023.
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Affiliation(s)
- Tahereh Mohammadian Gol
- University Children's Hospital, Department of Pediatrics I, Hematology and Oncology, University of Tübingen, Tübingen, Germany
| | - Fatemeh Zahedipour
- University Children's Hospital, Department of Pediatrics I, Hematology and Oncology, University of Tübingen, Tübingen, Germany; Department of Medical Biotechnology and Nanotechnology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Paul Trosien
- University Children's Hospital, Department of Pediatrics I, Hematology and Oncology, University of Tübingen, Tübingen, Germany
| | - Guillermo Ureña-Bailén
- University Children's Hospital, Department of Pediatrics I, Hematology and Oncology, University of Tübingen, Tübingen, Germany
| | - Miso Kim
- University Children's Hospital, Department of Pediatrics I, Hematology and Oncology, University of Tübingen, Tübingen, Germany
| | - Justin S Antony
- University Children's Hospital, Department of Pediatrics I, Hematology and Oncology, University of Tübingen, Tübingen, Germany
| | - Markus Mezger
- University Children's Hospital, Department of Pediatrics I, Hematology and Oncology, University of Tübingen, Tübingen, Germany.
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Magen I, Aharoni S, Yacovzada NS, Tokatly Latzer I, Alves CRR, Sagi L, Fattal-Valevski A, Swoboda KJ, Katz J, Bruckheimer E, Nevo Y, Hornstein E. Muscle microRNAs in the cerebrospinal fluid predict clinical response to nusinersen therapy in type II and type III spinal muscular atrophy patients. Eur J Neurol 2022; 29:2420-2430. [PMID: 35510740 PMCID: PMC9544362 DOI: 10.1111/ene.15382] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 04/13/2022] [Accepted: 04/28/2022] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The antisense oligonucleotide nusinersen (spinraza) regulates splicing of the survival motor neuron 2 (SMN2) messenger RNA to increase SMN protein expression and has improved ventilator free survival and motor function outcomes in infantile onset forms of SMA, treated early in the course of the disease. However, the response in later onset forms of SMA is highly variable and dependent on symptom severity and disease duration at treatment initiation. Therefore, we aimed to identify novel noninvasive biomarkers that could predict the response to nusinersen in type II and III SMA patients. METHODS 34 SMA patients were included. We applied next-generation sequencing to identify microRNAs in the cerebrospinal fluid (CSF) as candidate biomarkers predicting response to nusinersen. Hammersmith Functional Motor Scale Expanded (HFMSE), was conducted at baseline and 6 months post initiation of nusinersen therapy to assess motor function. Patients changing by ≥ 3 or ≤0 points in the HFMSE total score were considered as responders or non-responders, respectively. RESULTS Lower baseline levels of two muscle microRNAs (miR-206 and miR-133), alone or in combination, predicted the pre-determined clinical response to nusinersen after 6 months therapy. Moreover, miR-206 levels were inversely correlated with the HFMSE score. CONCLUSIONS Lower miR-206 and miR-133 in the CSF predict more robust clinical response to nusinersen treatment in later onset SMA patients. These novel findings have high clinical relevance for identifying early treatment response to nusinsersen in later onset SMA patients and call to test the ability of miRNAs to predict more sustained long-term benefit.
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Affiliation(s)
- Iddo Magen
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.,Department of Molecular Neuroscience, Weizmann Institute of Science, Rehovot, Israel
| | - Sharon Aharoni
- Institute of Pediatric Neurology, Schneider Children's Medical Center of Israel, Petach Tikva, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Nancy Sarah Yacovzada
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.,Department of Molecular Neuroscience, Weizmann Institute of Science, Rehovot, Israel
| | - Itay Tokatly Latzer
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.,Pediatric Neurology Institute, Dana-Dwek Children's Hospital, Tel Aviv Medical Center, Tel Aviv, Israel
| | - Christiano R R Alves
- Department of Neurology, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Liora Sagi
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.,Pediatric Neurology Institute, Dana-Dwek Children's Hospital, Tel Aviv Medical Center, Tel Aviv, Israel
| | - Aviva Fattal-Valevski
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.,Pediatric Neurology Institute, Dana-Dwek Children's Hospital, Tel Aviv Medical Center, Tel Aviv, Israel
| | - Kathryn J Swoboda
- Department of Neurology, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Jacob Katz
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.,Division of Department of Anesthesia, Schneider Children's Medical Center of Israel, Petach Tikva, Israel
| | - Elchanan Bruckheimer
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.,Cardiology Institute, Schneider Children's Medical Center of Israel, Petach Tikva, Israel
| | - Yoram Nevo
- Institute of Pediatric Neurology, Schneider Children's Medical Center of Israel, Petach Tikva, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Eran Hornstein
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.,Department of Molecular Neuroscience, Weizmann Institute of Science, Rehovot, Israel
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Velayudhan V, Patel S, Danziger A, Grigorian A, Waite S, Efendizade A. Transforaminal lumbar puncture for intrathecal access: Case series with literature review and comparison to other techniques. J Clin Neurosci 2020; 72:114-118. [PMID: 31980274 DOI: 10.1016/j.jocn.2019.12.056] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 12/30/2019] [Indexed: 11/30/2022]
Abstract
Fluoroscopic-guided lumbar puncture (LP) is a procedure commonly performed by radiologists, which in some circumstances may be difficult or impossible using a traditional posterior interspinous or interlaminar approach. Alternatives to LP include cervical and cisternal punctures, placement of an Ommaya reservoir, and lumbar laminectomy. More recently, however, there has been a move toward access of the thecal sac through a transforaminal approach in patients with challenging anatomy. This report outlines our approach and experience using transforaminal LP (TFLP) in patients with spinal muscular atrophy (SMA) with a 100% success rate. We discuss its utility in other patients with difficult access and compare TFLP with other techniques to access the intrathecal space.
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Affiliation(s)
- Vinodkumar Velayudhan
- Department of Diagnostic Radiology, SUNY Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203, United States.
| | - Suraj Patel
- Department of Diagnostic Radiology, SUNY Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203, United States
| | - Andrew Danziger
- Department of Neurosurgery, Temple University Hospital, 3401 North Broad Street, Philadelphia, PA 19140, United States
| | - Arcadi Grigorian
- Department of Diagnostic Radiology, SUNY Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203, United States
| | - Stephen Waite
- Department of Diagnostic Radiology, SUNY Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203, United States
| | - Aslan Efendizade
- Department of Diagnostic Radiology, SUNY Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203, United States
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Dabbous O, Maru B, Jansen JP, Lorenzi M, Cloutier M, Guérin A, Pivneva I, Wu EQ, Arjunji R, Feltner D, Sproule DM. Survival, Motor Function, and Motor Milestones: Comparison of AVXS-101 Relative to Nusinersen for the Treatment of Infants with Spinal Muscular Atrophy Type 1. Adv Ther 2019; 36:1164-1176. [PMID: 30879249 PMCID: PMC6824368 DOI: 10.1007/s12325-019-00923-8] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Indexed: 11/17/2022]
Abstract
Introduction Infants with spinal muscular atrophy (SMA) type 1 typically face a decline in motor function and a severely shortened life expectancy. Clinical trials for SMA type 1 therapies, onasemnogene abeparvovec (AVXS-101) and nusinersen, demonstrated meaningful improvements in efficacy (e.g., overall survival) but there were no head-to-head clinical trials assessing comparative efficacy. This study estimated the treatment effects of AVXS-101 relative to nusinersen for the treatment of SMA type 1. Methods Overall survival, event-free survival (no death or need to use permanent assisted ventilation), improvement in motor function [increase of ≥ 4 points in Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) score from baseline], and motor milestone achievements (head control, rolling over, and sitting unassisted) reported in the onasemnogene abeparvovec (AVXS-101-CL-101; NCT02122952) and nusinersen (ENDEAR; NCT02193074) clinical trials were indirectly compared using frequentist and Bayesian approaches. Results Among symptomatic infants with SMA type 1, the number needed to treat (NNT) to prevent one more death with AVXS-101 instead of nusinersen was 6.2 [95% confidence intervals (CI) = 4.1–12.2], and the probability of preventing death was 20% higher for patients treated with AVXS-101 than nusinersen [risk ratio (RR) = 1.2, 95% CI 1.1–1.3]. For event-free survival, the NNT to prevent one more event was 2.6 (95% CI 2.0–3.6) and RR was 1.6 (95% CI 1.4–1.9). For improvement in motor function, NNT was 3.5 (95% CI 2.6–5.3) and RR was 1.4 (95% CI 1.2–1.6). For milestone achievements, the NNTs were 1.4 (95% CI 1.1–1.9), 1.5 (95% CI 1.1–2.5), and 1.2 (95% CI 1.0–1.5); RRs 4.2 (95% CI 2.6–6.7), 7.8 (95% CI 3.6–17.0), and 11.2 (95% CI 5.1–24.5) for head control, rolling over, and sitting unassisted, respectively. Results were similar using the Bayesian approach. Conclusion This indirect comparison (AVXS-101-CL-101 vs. ENDEAR) among symptomatic SMA type 1 infants suggests that AVXS-101 may have an efficacy advantage relative to nusinersen for overall survival, independence from permanent assisted ventilation, motor function, and motor milestones. Funding AveXis.
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Andrews JA, Shefner JM. Clinical neurophysiology of anterior horn cell disorders. HANDBOOK OF CLINICAL NEUROLOGY 2019; 161:317-326. [PMID: 31307610 DOI: 10.1016/b978-0-444-64142-7.00057-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The development of neurophysiological techniques for clinical assessment in the 20th century is closely related to the study of anterior horn cell diseases. The effects of motor axon loss on nerve conduction velocity and compound motor amplitude were elucidated first in amyotrophic lateral sclerosis (ALS), as was the characterization of reinnervation as detected by needle electromyography. The same changes noted in early studies still play a major role in the diagnosis of anterior horn cell diseases. In addition, much of modern neurophysiological assessment of motor axon quantitation, ion channel changes in neurogenic disease, and cortical physiology studies to assess both network and excitability abnormalities have all been applied to ALS. In this chapter, we summarize the clinical attributes of ALS and Spinal Muscular Atrophy, and review how clinical neurophysiology is employed in the clinical and the research setting.
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Affiliation(s)
- Jinsy A Andrews
- The Neurological Institute, Columbia University, New York, NY, United States
| | - Jeremy M Shefner
- Department of Neurology, Barrow Neurological Institute, Phoenix, AZ, United States.
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De Paola E, Verdile V, Paronetto MP. Dysregulation of microRNA metabolism in motor neuron diseases: Novel biomarkers and potential therapeutics. Noncoding RNA Res 2018; 4:15-22. [PMID: 30891533 PMCID: PMC6404378 DOI: 10.1016/j.ncrna.2018.12.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 12/18/2018] [Accepted: 12/19/2018] [Indexed: 12/11/2022] Open
Abstract
In the last 15 years, several classes of small regulatory RNAs have been identified, uncovering the widespread impact of non-coding elements in the human genome on cell homeostasis and human diseases. MicroRNAs (miRNAs) are a family of small, non-coding RNAs, which exert silencing of mRNA targets in a sequence-dependent fashion. Many miRNAs are specifically expressed in the central nervous system, where they display roles in differentiation, neuronal survival, neuronal plasticity and learning. On the other hand, deregulated miRNA/mRNA expression networks are deeply involved in neurodegeneration. Recent findings suggest a role for miRNAs in the pathogenesis of motor neuron diseases. In particular, cell-specific changes in miRNA profile are involved in the motor neuron disease phenotype and might be implicated in their selective vulnerability. Exploitation of noncoding RNAs, in particular miRNAs, for therapeutic strategies is being assessed for implementing current therapies. In this regard, the neuroprotective potential of certain miRNAs could represent a promising potential tool to improve therapies for motor-neuron diseases. This review focuses on emerging roles of miRNAs in motor neuron diseases and on their impact on neuron life-span and integrity.
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Affiliation(s)
- Elisa De Paola
- University of Rome "Foro Italico", Piazza Lauro de Bosis 15, 00135, Rome, Italy.,Laboratory of Cellular and Molecular Neurobiology, Fondazione Santa Lucia, Via del Fosso di Fiorano, 64, 00143, Rome, Italy
| | - Veronica Verdile
- University of Rome "Foro Italico", Piazza Lauro de Bosis 15, 00135, Rome, Italy.,Laboratory of Cellular and Molecular Neurobiology, Fondazione Santa Lucia, Via del Fosso di Fiorano, 64, 00143, Rome, Italy
| | - Maria Paola Paronetto
- University of Rome "Foro Italico", Piazza Lauro de Bosis 15, 00135, Rome, Italy.,Laboratory of Cellular and Molecular Neurobiology, Fondazione Santa Lucia, Via del Fosso di Fiorano, 64, 00143, Rome, Italy
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Falsaperla R, Vitaliti G, Collotta AD, Fiorillo C, Pulvirenti A, Alaimo S, Romano C, Ruggieri M. Electrocardiographic Evaluation in Patients With Spinal Muscular Atrophy: A Case-Control Study. J Child Neurol 2018; 33:487-492. [PMID: 29687752 DOI: 10.1177/0883073818767170] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND This study aimed to show the impairment of autonomic cardiac conduction causing bradycardia and/or electrocardiographic alterations in children affected by spinal muscular atrophy type 1 and 2 (SMA 1 and 2). METHODS We included 25 spinal muscular atrophy patients, admitted from November 2016 to May 2017. All patients underwent an electrocardiographic examination and we studied PR and QRS intervals, P-waves and QRS amplitudes, and heart rate in spinal muscular atrophy patients compared to a control group. RESULTS In all patients, we found longer PRi and QRSi ( P < .05), lower P-wave and QRS complex amplitudes ( P < .01), and a decreased heart rate ( P < .01) with respect to controls. When we divided our patients into SMA1 and SMA2 subgroups, we found that statistical differences were maintained for P-wave and QRS complex amplitudes and heart rate, but not for PRi and QRSi with respect to controls. CONCLUSION We suggest the hypothesis of SMN expression on cardiac tissue condition and/or autonomic cardiac conduction.
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Affiliation(s)
- Raffaele Falsaperla
- 1 General Pediatrics and Pediatric Acute and Emergency Complex Unit, Policlinico-Vittorio-Emanuele University Hospital, University of Catania, Italy
| | - Giovanna Vitaliti
- 1 General Pediatrics and Pediatric Acute and Emergency Complex Unit, Policlinico-Vittorio-Emanuele University Hospital, University of Catania, Italy
| | - Ausilia Desiree Collotta
- 1 General Pediatrics and Pediatric Acute and Emergency Complex Unit, Policlinico-Vittorio-Emanuele University Hospital, University of Catania, Italy
| | - Chiara Fiorillo
- 2 Unit of Paediatric Neurology and Muscle Diseases, G. Gaslini Institute, Genoa, Italy
| | - Alfredo Pulvirenti
- 3 Department of Clinical and Experimental Medicine, Section of Bioinformatics, University of Catania, Italy
| | - Salvatore Alaimo
- 3 Department of Clinical and Experimental Medicine, Section of Bioinformatics, University of Catania, Italy
| | - Catia Romano
- 1 General Pediatrics and Pediatric Acute and Emergency Complex Unit, Policlinico-Vittorio-Emanuele University Hospital, University of Catania, Italy
| | - Martino Ruggieri
- 4 Unit of Rare Diseases of the Nervous System in Childhood, Policlinico-Vittorio-Emanuele University Hospital, University of Catania, Italy
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Hunter M, Heatwole C, Luebbe E, Johnson NE. What Matters Most: A Perspective From Adult Spinal Muscular Atrophy Patients. J Neuromuscul Dis 2018; 3:425-429. [PMID: 27854231 DOI: 10.3233/jnd-160168] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
There are multiple symptoms that affect adults with spinal muscular atrophy (SMA). The extent of these symptoms and their impact on individuals' lives is not fully known. We interviewed 15 adults with genetically confirmed SMA. Participants were asked to identify issues that have significant impact on their lives. Interviews were recorded, transcribed, coded, and analyzed. Participants provided 1045 direct quotes. 177 potential symptoms of importance were identified. Symptoms were grouped by like topics into fourteen symptomatic themes. The symptoms and issues identified by SMA patients alter their physical, mental, and social health and may be amendable to therapeutic intervention.
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Affiliation(s)
- Michael Hunter
- Department of Neurology, University of Utah School of Medicine, North Medical Drive East, Salt Lake City, UT, USA
| | - Chad Heatwole
- Department of Neurology, University of Rochester School of Medicine and Dentistry, Elmwood Ave, Rochester, NY, USA
| | - Elizabeth Luebbe
- Department of Neurology, University of Rochester School of Medicine and Dentistry, Elmwood Ave, Rochester, NY, USA
| | - Nicholas E Johnson
- Department of Neurology, University of Utah School of Medicine, North Medical Drive East, Salt Lake City, UT, USA
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Boardman FK, Sadler C, Young PJ. Newborn genetic screening for spinal muscular atrophy in the UK: The views of the general population. Mol Genet Genomic Med 2017; 6:99-108. [PMID: 29169204 PMCID: PMC5823674 DOI: 10.1002/mgg3.353] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Revised: 10/12/2017] [Accepted: 10/26/2017] [Indexed: 12/16/2022] Open
Abstract
Background Spinal muscular atrophy (SMA) is an inherited neuromuscular disorder and a leading genetic cause of infant death worldwide. However, there is no routine screening program for SMA in the UK. Lack of treatments and the inability of screening tests to accurately predict disease severity are among the key reasons implementation of screening has faltered in the UK. With the recent release of the first therapy for SMA (Nusinersen), calls are being made for a reconsideration of this stance; however, very little is known about the views of the general public. Methods An online survey was administered to 232 individuals with no prior relationship with SMA to assess their attitudes toward a newborn screening program for it. Results are compared with previously gathered data on the views of SMA‐affected families toward screening. Results Eighty‐four percent of participants were in favor of newborn screening. Key reasons for support were a belief that it would lead to better healthcare and life expectancy for affected infants and facilitate informed decision‐making for future pregnancies. Key reasons for nonsupport were a belief in the potential for significant negative impact on the family unit in terms of bonding and stress. Conclusions Public acceptability is a key component in the evaluation of any potential screening program in the UK. This study demonstrates that newborn screening for SMA is viewed largely positively by people unfamiliar with the condition. The importance of early identification overrode all other social and ethical concerns about screening for the majority of participants.
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Affiliation(s)
- Felicity K Boardman
- Division of Health Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Chloe Sadler
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Philip J Young
- School of Life Sciences, University of Warwick, Coventry, UK
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Verhaart IEC, Robertson A, Wilson IJ, Aartsma-Rus A, Cameron S, Jones CC, Cook SF, Lochmüller H. Prevalence, incidence and carrier frequency of 5q-linked spinal muscular atrophy - a literature review. Orphanet J Rare Dis 2017; 12:124. [PMID: 28676062 PMCID: PMC5496354 DOI: 10.1186/s13023-017-0671-8] [Citation(s) in RCA: 370] [Impact Index Per Article: 52.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 06/13/2017] [Indexed: 12/14/2022] Open
Abstract
Spinal muscular atrophy linked to chromosome 5q (SMA) is a recessive, progressive, neuromuscular disorder caused by bi-allelic mutations in the SMN1 gene, resulting in motor neuron degeneration and variable presentation in relation to onset and severity. A prevalence of approximately 1-2 per 100,000 persons and incidence around 1 in 10,000 live births have been estimated with SMA type I accounting for around 60% of all cases. Since SMA is a relatively rare condition, studies of its prevalence and incidence are challenging. Most published studies are outdated and therefore rely on clinical rather than genetic diagnosis. Furthermore they are performed in small cohorts in small geographical regions and only study European populations. In addition, the heterogeneity of the condition can lead to delays and difficulties in diagnosing the condition, especially outside of specialist clinics, and contributes to the challenges in understanding the epidemiology of the disease. The frequency of unaffected, heterozygous carriers of the SMN1 mutations appears to be higher among Caucasian and Asian populations compared to the Black (Sub-Saharan African ancestry) population. However, carrier frequencies cannot directly be translated into incidence and prevalence, as very severe (death in utero) and very mild (symptom free in adults) phenotypes carrying bi-allelic SMN1 mutations exist, and their frequency is unknown. More robust epidemiological data on SMA covering larger populations based on accurate genetic diagnosis or newborn screening would be helpful to support planning of clinical studies, provision of care and therapies and evaluation of outcomes.
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Affiliation(s)
- Ingrid E. C. Verhaart
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Agata Robertson
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Ian J. Wilson
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Annemieke Aartsma-Rus
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Shona Cameron
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | | | | | - Hanns Lochmüller
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
- John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ UK
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Kichula EA. Inherited Neuromuscular Disorders: Presentation, Diagnosis, and Advances in Treatment. CURRENT PEDIATRICS REPORTS 2017. [DOI: 10.1007/s40124-017-0118-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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13
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RASHNONEJAD A, ONAY H, ATIK T, ATAN SAHIN O, GOKBEN S, TEKGUL H, OZKINAY F. Molecular Genetic Analysis of Survival Motor Neuron Gene in 460 Turkish Cases with Suspicious Spinal Muscular Atrophy Disease. IRANIAN JOURNAL OF CHILD NEUROLOGY 2016; 10:30-35. [PMID: 27843464 PMCID: PMC5100035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE To describe 12 yr experience of molecular genetic diagnosis of Spinal Muscular Atrophy (SMA) in 460 cases of Turkish patients. MATERIALS & METHODS A retrospective analysis was performed on data from 460 cases, referred to Medical Genetics Laboratory, Ege University's Hospital, Izmir, Turkey, prediagnosed as SMA or with family history of SMA between 2003 and 2014. The PCR-restriction fragment length polymorphism (RFLP) and the Multiplex ligation-dependent probe amplification (MLPA) analysis were performed to detect the survival motor neuron (SMN)1 deletions and to estimate SMN1 and SMN2 gene copy numbers. RESULTS Using PCR-RFLP test, 159 of 324 postnatal and 18 of 77 prenatal cases were detected to have SMN1 deletions. From positive samples, 88.13% had a homozygous deletion in both exon 7 and exon 8 of SMN1. Using MLPA, 54.5% of families revealed heterozygous deletions of SMN1, and 2 or 3 copies of SMN2, suggesting a healthy SMA carrier. Among patients referred for SMA testing, the annual percentage of patients diagnosed as SMA has decreased gradually from 90.62% (2003) down to 20.83% (2014). CONCLUSION Although PCR-RFLP method is a reliable test for SMA screening, MLPA is a necessary additional test and provide relevant data for genetic counseling of families having previously affected child. The gradual decrease in the percentage of patients molecularly diagnosed as SMA shows that clinicians have begun to use genetic tests in the differential diagnosis of muscular atrophies. Cost and availability of these genetic tests has greatly attributed to their use.
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Affiliation(s)
- Afrooz RASHNONEJAD
- 1.Young Researchers and Elites Club, North Tehran Branch, Islamic Azad University, Tehran, Iran
| | - Huseyin ONAY
- Department of Medical Genetics, Faculty of Medicine, Ege University, Izmir, Turkey
| | - Tahir ATIK
- Department of Pediatrics, Faculty of medicine, Ege University, Izmir, Turkey
| | - Ozlem ATAN SAHIN
- Department of molecular biology and biochemistry, health Sciences Institute, Acibadem University, Istanbul, Tureky
| | - Sarenur GOKBEN
- Division of Child Neurology, Department of Pediatrics, faculty of medicine, Ege University, Izmir, Turkey
| | - Hasan TEKGUL
- Division of Child Neurology, Department of Pediatrics, faculty of medicine, Ege University, Izmir, Turkey
| | - Ferda OZKINAY
- Department of Medical Genetics, Faculty of Medicine, Ege University, Izmir, Turkey,Department of Pediatrics, Faculty of medicine, Ege University, Izmir, Turkey
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Carré A, Empey C. Review of Spinal Muscular Atrophy (SMA) for Prenatal and Pediatric Genetic Counselors. J Genet Couns 2015; 25:32-43. [DOI: 10.1007/s10897-015-9859-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 06/30/2015] [Indexed: 11/29/2022]
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15
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MacDonald WK, Hamilton D, Kuhle S. SMA carrier testing: a meta-analysis of differences in test performance by ethnic group. Prenat Diagn 2014; 34:1219-26. [DOI: 10.1002/pd.4459] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 07/03/2014] [Accepted: 07/07/2014] [Indexed: 02/05/2023]
Affiliation(s)
| | - David Hamilton
- Department of Mathematics and Statistics; Dalhousie University; Halifax NS Canada
| | - Stefan Kuhle
- Department of Obstetrics & Gynaecology; Dalhousie University; Halifax NS Canada
- Department of Pediatrics; Dalhousie University; Halifax NS Canada
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16
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Luo M, Liu L, Peter I, Zhu J, Scott SA, Zhao G, Eversley C, Kornreich R, Desnick RJ, Edelmann L. An Ashkenazi Jewish SMN1 haplotype specific to duplication alleles improves pan-ethnic carrier screening for spinal muscular atrophy. Genet Med 2013; 16:149-56. [PMID: 23788250 DOI: 10.1038/gim.2013.84] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Accepted: 05/02/2013] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Spinal muscular atrophy is a common autosomal-recessive disorder caused by mutations of the SMN1 gene. Spinal muscular atrophy carrier screening uses dosage-sensitive methods that determine SMN1 copy number, and the frequency of carriers varies by ethnicity, with detection rates ranging from 71 to 94% due to the inability to identify silent (2 + 0) carriers with two copies of SMN1 on one chromosome 5 and deletion on the other. We hypothesized that identification of deletion and/or duplication founder alleles might provide an approach to identify silent carriers in various ethnic groups. METHODS SMN1 founder alleles were investigated in the Ashkenazi Jewish population by microsatellite analysis and next-generation sequencing. RESULTS An extended haplotype block, specific to Ashkenazi Jewish SMN1 duplications, was identified by microsatellite analysis, and next-generation sequencing of SMN1 further defined a more localized haplotype. Of note, six novel SMN1 sequence variants were identified that were specific to duplications and not present on single-copy alleles. The haplotype was also identified on SMN1 duplication alleles in additional ethnic groups. CONCLUSION Identification of these novel variants in an individual with two copies of SMN1 significantly improves the accuracy of residual risk estimates and has important implications for spinal muscular atrophy carrier screening.
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Affiliation(s)
- Minjie Luo
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine of New York University, New York, New York, USA
| | - Liu Liu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Inga Peter
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine of New York University, New York, New York, USA
| | - Jun Zhu
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine of New York University, New York, New York, USA
| | - Stuart A Scott
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine of New York University, New York, New York, USA
| | - Geping Zhao
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine of New York University, New York, New York, USA
| | | | - Ruth Kornreich
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine of New York University, New York, New York, USA
| | - Robert J Desnick
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine of New York University, New York, New York, USA
| | - Lisa Edelmann
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine of New York University, New York, New York, USA
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17
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Jiang W, Ji X, Xu Y, Qu X, Sun W, Yang Z, Tao J, Chen Y. Molecular prenatal diagnosis of autosomal recessive spinal muscular atrophies using quantification polymerase chain reaction. Genet Test Mol Biomarkers 2013; 17:438-42. [PMID: 23448387 DOI: 10.1089/gtmb.2012.0481] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder characterized by degeneration of alpha motor neurons in the spinal cord, resulting in progressive proximal muscle weakness and paralysis. SMA is the second most common neuromuscular disorder and a common cause of infant disability and mortality. About 95% of patients have a homozygous deletion of exon7 in the survival motor neuron 1 gene. About 50 fetuses from 47 Chinese couples at risk of having an affected child were recruited in this study. The homozygous absence of exon7 of the survival motor neuron 1 gene was detected by both polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and the quantitative PCR method. Short tandem repeat microsatellite markers linked to the survival motor neuron 1 gene were used to do linkage analysis. In conclusion, the quantitative PCR method results were as reliable as the results using the PCR-RFLP method in prenatal diagnosis. The quantitative PCR method can give more information on SMA carrier status that coincides with the result of linkage analysis.
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Affiliation(s)
- Wenting Jiang
- Department of Prenatal Diagnosis Center, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
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18
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Pan-ethnic carrier screening and prenatal diagnosis for spinal muscular atrophy: clinical laboratory analysis of >72,400 specimens. Eur J Hum Genet 2011; 20:27-32. [PMID: 21811307 PMCID: PMC3234503 DOI: 10.1038/ejhg.2011.134] [Citation(s) in RCA: 420] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a leading inherited cause of infant death with a reported incidence of ∼1 in 10 000 live births and is second to cystic fibrosis as a common, life-shortening autosomal recessive disorder. The American College of Medical Genetics has recommended population carrier screening for SMA, regardless of race or ethnicity, to facilitate informed reproductive options, although other organizations have cited the need for additional large-scale studies before widespread implementation. We report our data from carrier testing (n=72 453) and prenatal diagnosis (n=121) for this condition. Our analysis of large-scale population carrier screening data (n=68 471) demonstrates the technical feasibility of high throughput testing and provides mutation carrier and allele frequencies at a level of accuracy afforded by large data sets. In our United States pan-ethnic population, the calculated a priori carrier frequency of SMA is 1/54 with a detection rate of 91.2%, and the pan-ethnic disease incidence is calculated to be 1/11 000. Carrier frequency and detection rates provided for six major ethnic groups in the United States range from 1/47 and 94.8% in the Caucasian population to 1/72 and 70.5% in the African American population, respectively. This collective experience can be utilized to facilitate accurate pre- and post-test counseling in the settings of carrier screening and prenatal diagnosis for SMA.
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19
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Establishment of a molecular diagnostic system for spinal muscular atrophy experience from a clinical laboratory in china. J Mol Diagn 2010; 13:41-7. [PMID: 21227393 DOI: 10.1016/j.jmoldx.2010.11.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 06/27/2010] [Accepted: 07/30/2010] [Indexed: 01/22/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a common autosomal recessive neuromuscular disorder characterized by degeneration of the anterior horn of the spinal cord. The disease gene survival motor neuron 1 (SMN1) is homozygously absent in approximately 95% of patients, and approximately 5% of patients are believed to have subtle mutations. Although methods for molecular diagnosis of SMA have been reported singly, no diagnostic methodological system to tackle different SMA cases has been reported. Thirty-two families affected by SMA enrolled into this study. Our system comprised PCR-restriction fragment length polymorphism and allele-specific PCR for homozygous deletion analysis of SMN1, multiplex ligation-dependent probe amplification analysis for the determination of the copy number of SMN1, and SMN1 subtle mutation analysis at both the transcript and genomic levels. In 23 families, 21 patients had a homozygous deletion of SMN1. The remaining two patients without a deletion had a single SMN1 copy containing the subtle mutations S230L and L228X, respectively. In nine families in whom samples from the index patients were unavailable, parents from eight families showed one SMN1 copy, and one parent in the remaining family showed two SMN1 copies, one being normal and the other carrying the subtle mutation 22_23insA. To our knowledge, our methodological system for the molecular diagnosis of SMA offers the most complete evaluation of family members affected by SMA at this time.
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20
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Hendrickson BC, Donohoe C, Akmaev VR, Sugarman EA, Labrousse P, Boguslavskiy L, Flynn K, Rohlfs EM, Walker A, Allitto B, Sears C, Scholl T. Differences in SMN1 allele frequencies among ethnic groups within North America. J Med Genet 2009; 46:641-4. [PMID: 19625283 PMCID: PMC2729371 DOI: 10.1136/jmg.2009.066969] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Background: Spinal muscular atrophy (SMA) is the most common inherited lethal disease of children. Various genetic deletions involving the bi-allelic loss of SMN1 exon 7 are reported to account for 94% of affected individuals. Published literature places the carrier frequency for SMN1 mutations between 1 in 25 and 1 in 50 in the general population. Although SMA is considered to be a pan-ethnic disease, carrier frequencies for many ethnicities, including most ethnic groups in North America, are unknown. Objectives and methods: To provide an accurate assessment of SMN1 mutation carrier frequencies in African American, Ashkenazi Jewish, Asian, Caucasian, and Hispanic populations, more than 1000 specimens in each ethnic group were tested using a clinically validated, quantitative real-time polymerase chain reaction (PCR) assay that measures exon 7 copy number. Results: The observed one-copy genotype frequency was 1 in 37 (2.7%) in Caucasian, 1 in 46 (2.2%) in Ashkenazi Jew, 1 in 56 (1.8%) in Asian, 1 in 91 (1.1%) in African American, and 1 in 125 (0.8%) in Hispanic specimens. Additionally, an unusually high frequency of alleles with multiple copies of SMN1 was identified in the African American group (27% compared to 3.3–8.1%). This latter finding has clinical implications for providing accurate adjusted genetic risk assessments to the African American population. Conclusions: Differences in the frequency of SMA carriers were significant among several ethnic groups. This study provides an accurate assessment of allele frequencies and estimates of adjusted genetic risk that were previously unavailable to clinicians and patients considering testing.
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Affiliation(s)
| | - C Donohoe
- Genzyme Genetics, Westborough, Massachusetts, USA
| | - V R Akmaev
- Genzyme Genetics, Westborough, Massachusetts, USA
| | - E A Sugarman
- Genzyme Genetics, Westborough, Massachusetts, USA
| | - P Labrousse
- Genzyme Genetics, Westborough, Massachusetts, USA
| | | | - K Flynn
- Genzyme Genetics, Westborough, Massachusetts, USA
| | - E M Rohlfs
- Genzyme Genetics, Westborough, Massachusetts, USA
| | - A Walker
- Genzyme Genetics, Westborough, Massachusetts, USA
| | - B Allitto
- Genzyme Genetics, Westborough, Massachusetts, USA
| | - C Sears
- Department of Hematology and Oncology, Children’s Hospital, Boston, Massachusetts, USA
- Broad Institute, Cancer Program, Cambridge, Massachusetts, USA
| | - T Scholl
- Genzyme Genetics, Westborough, Massachusetts, USA
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21
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Zeng J, Lan F, Deng X, Ke L, Tu X, Huang L, Zheng D, Zhu Z. Evaluation of an in-house protocol for prenatal molecular diagnosis of SMA in Chinese. Clin Chim Acta 2008; 398:78-81. [DOI: 10.1016/j.cca.2008.08.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Revised: 08/18/2008] [Accepted: 08/18/2008] [Indexed: 11/16/2022]
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22
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Alias L, Barceló MJ, Gich I, Estapé M, Parra J, Amenedo M, Baiget M, Tizzano EF. Evidence of a segregation ratio distortion of SMN1 alleles in spinal muscular atrophy. Eur J Hum Genet 2007; 15:1090-3. [PMID: 17625510 DOI: 10.1038/sj.ejhg.5201886] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive disorder characterised by degeneration and loss of the motor neurons of the anterior horn of the spinal cord. The absence of SMN1 is determinant to have SMA and parents of SMA patients are regarded as carriers of the disease. We compared the segregation ratio of the mutated allele and the wild-type allele of all the confirmed carrier parents assuming Mendelian proportions. Results of transmissions in 235 prenatal tests and in 128 unaffected siblings showed a statistically significant deviation in favour of the wild-type SMN1 allele. The number of affected foetuses and carriers were lower than that expected. No significant differences in the sex ratio or in the progenitor origin of the transmitted allele to the carriers were found. One hypothesis that has been advanced to account for the distortion observed in affected foetuses is the negative postzygote selection due to early miscarriage. However, given that the number of carriers in our series was lower than expected, prezygote events such as meiotic drive, survival of gametes or preferential fertilisation should also be considered.
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Affiliation(s)
- Laura Alias
- Department of Genetics, Hospital de Sant Pau, Barcelona, Spain
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23
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Clermont O, Burlet P, Benit P, Chanterau D, Saugier-Veber P, Munnich A, Cusin V. Molecular analysis of SMA patients without homozygous SMN1 deletions using a new strategy for identification of SMN1 subtle mutations. Hum Mutat 2005; 24:417-27. [PMID: 15459957 DOI: 10.1002/humu.20092] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Spinal muscular atrophy (SMA) is a common autosomal recessive disease. SMA is linked to the 5q13 locus in 95% of patients, and in at least 98% of them, the SMN1 homozygous deletion is found. Compound heterozygous patients, who have an SMN1 deletion associated with a subtle mutation, appear undeleted with the common molecular diagnostic test that detects only the homozygous absence of SMN1. In these patients, mutation screening in SMN1 is hampered by the presence of several copies of the highly homologous SMN2 gene. Here, we present a rapid and reliable strategy for detecting SMN mutations using long-range PCR, which avoids cloning and cDNA analysis. Using this method, we found 10 mutations, including five mutations never reported previously and five recurrent mutations; some of them are probably population-specific. Marker analysis of the 5q13 locus in these mutations showed common haplotypes, supporting the hypothesis of a common ancestor rather than a hot spot sequence. We also evaluate the suitability of automated SSCA and DHPLC for mutation scanning.
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24
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Kesari A, Misra UK, Kalita J, Mishra VN, Pradhan S, Patil SJ, Phadke SR, Mittal B. Study of survival of motor neuron (SMN) and neuronal apoptosis inhibitory protein (NAIP) gene deletions in SMA patients. J Neurol 2005; 252:667-71. [PMID: 15772743 DOI: 10.1007/s00415-005-0714-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2004] [Revised: 10/14/2004] [Accepted: 10/26/2004] [Indexed: 12/22/2022]
Abstract
In view of the paucity of deletion studies of survival of motor neuron (SMN) and neuronal apoptosis inhibitor protein (NAIP) genes in Indian SMA patients, this study has been undertaken to determine the status of SMN1, SMN2 and NAIP gene deletions in Indian SMA patients. Clinically and neurophysiologically diagnosed SMA patients were included in the study. A gene deletion study was carried out in 45 proximal SMA patients and 50 controls of the same ethnic group. Both SMN1 and NAIP genes showed homozygous absence in 76% and 31% respectively in proximal SMA patients. It is proposed that the lower deletion frequency of SMN1 gene in Indian patients may be due to mutations present in other genes or population variation, which need further study.
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Affiliation(s)
- Akanchha Kesari
- Dept. of Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Raebareli Road, Lucknow-226014, India
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25
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Ogino S, Wilson RB, Gold B. New insights on the evolution of the SMN1 and SMN2 region: simulation and meta-analysis for allele and haplotype frequency calculations. Eur J Hum Genet 2004; 12:1015-23. [PMID: 15470363 DOI: 10.1038/sj.ejhg.5201288] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Most spinal muscular atrophy patients lack both copies of SMN1. Loss of SMN1 ('0-copy alleles') can occur by gene deletion or SMN1-to-SMN2 gene conversion. Despite worldwide efforts to map the segmental duplications within the SMN region, most assemblies do not correctly delineate these genes. A near pericentromeric location provides impetus for the strong evidence that SMN1 and SMN2 arose from a primate-specific paralogous gene duplication. Here we meta-analyzed our recent laboratory results together with available published data, in order to calculate new mutation rates and allele/haplotype frequencies in this recalcitrant and highly unstable region of the human genome. Based on our tested assumption of compliance with Hardy-Weinberg equilibrium, we conclude that the SMN1 allele frequencies are: '0-copy disease alleles,' 0.013; '1-copy normal alleles,' 0.95; '2-copy normal alleles (ie, two copies of SMN1 on one chromosome),' 0.038; and '1(D) disease alleles (SMN1 with a small intragenic mutation),' 0.00024. The SMN1 haplotype ['(SMN1 copy number)-(SMN2 copy number)'] frequencies are: '0-0,' 0.00048; '0-1,' 0.0086; '0-2,' 0.0042; '1-0,' 0.27; '1-1,' 0.66; '1-2,' 0.015; '2-0,' 0.027; and '2-1,' 0.012. Paternal and maternal de novo mutation rates are 2.1 x 10(-4) and 4.2 x 10(-5), respectively. Our data provide the basis for the most accurate genetic risk calculations, as well as new insights on the evolution of the SMN region, with evidence that nucleotide position 840 (where a transition 840C>T functionally distinguishes SMN2 from SMN1) constitutes a mutation hotspot. Our data also suggest selection of the 1-1 haplotype and the presence of rare chromosomes with three copies of SMN1.
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Affiliation(s)
- Shuji Ogino
- Department of Pathology, Brigham and Women's Hospital, Boston, MA 02115, USA.
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Ogino S, Gao S, Leonard DGB, Paessler M, Wilson RB. Inverse correlation between SMN1 and SMN2 copy numbers: evidence for gene conversion from SMN2 to SMN1. Eur J Hum Genet 2003; 11:275-7. [PMID: 12673282 DOI: 10.1038/sj.ejhg.5200957] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Most carriers of autosomal recessive spinal muscular atrophy (SMA) have only one copy of SMN1 because of SMN1 gene deletions or gene conversions from SMN1 to SMN2, which has only one base difference in coding sequence from SMN1. Using SMN gene dosage analysis, we determined the copy numbers of SMN1 and SMN2 in the general population as well as in SMA patients and carriers. Increased SMN1 copy number is associated with decreased SMN2 copy number in the general population; that is, SMN2 copy number was decreased to one or zero copies in 11 of 13 individuals with three or four copies of SMN1, whereas only 71 of 164 individuals with two copies of SMN1 had one or zero copies of SMN2 (P<0.01). SMN2 copy number was increased to three or four in a subset of SMN1 deletion/conversion carriers, and in most SMA patients with a milder phenotype. In conclusion, our data provide evidence that gene conversion from SMN2 to SMN1 occurs, and that SMN1 converted from SMN2 is present in the general population.
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Affiliation(s)
- Shuji Ogino
- Department of Pathology, Brigham and Women's Hospital, Boston, MA 02115, USA.
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Ogino S, Wilson RB. Quantification of PCR bias caused by a single nucleotide polymorphism in SMN gene dosage analysis. J Mol Diagn 2002; 4:185-90. [PMID: 12411585 PMCID: PMC3278980 DOI: 10.1016/s1525-1578(10)60702-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Approximately 94% of patients with spinal muscular atrophy lack both copies of SMN1 exon 7, and most carriers have only one copy of SMN1 exon 7. We described previously the effect of SMN1/SMN2 heteroduplex formation on SMN gene dosage analysis, which is a multiplex quantitative PCR assay to determine the copy numbers of SMN1 and SMN2 using DraI digestion to differentiate SMN2 from SMN1. We describe herein the quantification of PCR bias between SMN1 exon 7 and SMN2 exon 7, which differ by only one nucleotide that is not present in either primer binding site. Using samples from 272 individuals with various SMN genotypes, we found that the amplification efficiency of SMN2 was consistent only approximately 80% that of SMN1. Thus, even a single nucleotide polymorphism, not in primer binding sites, can cause reproducible PCR bias. The precision and accuracy of our SMN gene dosage analysis are high because our assay design and controls take advantage of the consistency of the PCR bias. As additional clinically significant single nucleotide polymorphisms (SNPs) are discovered, assessment of PCR bias, and judicious selection of standards and controls, will be increasingly important for quantitative PCR assays.
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Affiliation(s)
- Shuji Ogino
- Department of Pathology, Brigham and Women's Hospital, Boston, MA 02115, USA.
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Ogino S, Leonard DGB, Rennert H, Ewens WJ, Wilson RB. Genetic risk assessment in carrier testing for spinal muscular atrophy. AMERICAN JOURNAL OF MEDICAL GENETICS 2002; 110:301-7. [PMID: 12116201 DOI: 10.1002/ajmg.10425] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
As evidenced by the complete absence of a functionally critical sequence in exon 7, approximately 94% of individuals with clinically typical spinal muscular atrophy (SMA) lack both copies of the SMN1 gene at 5q13. Hence most carriers have only one copy of SMN1. Combining linkage and dosage analyses for SMN1, we observed unaffected individuals who have two copies of SMN1 on one chromosome 5 and zero copies of SMN1 on the other chromosome 5. By dosage analysis alone, such individuals, as well as carriers of non-deletion disease alleles, are indistinguishable from non-carrier individuals. We report that approximately 7% of unaffected individuals without a family history of SMA have three or four copies of SMN1, implying a higher frequency of chromosomes with two copies of SMN1 than previously reported. We present updated calculations for disease and non-disease allele frequencies and we describe how these frequencies can be used for genetic risk assessment in carrier testing for SMA.
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Affiliation(s)
- Shuji Ogino
- Molecular Pathology Laboratory, Department of Pathology and Laboratory Medicine, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania, USA
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29
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Ogino S, Wilson RB. SMN dosage analysis and risk assessment for spinal muscular atrophy. Am J Hum Genet 2002; 70:1596-8; author reply 1598-9. [PMID: 11992267 PMCID: PMC379149 DOI: 10.1086/340789] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Affiliation(s)
- Shuji Ogino
- Department of Pathology, Brigham and Women’s Hospital, Department of Adult Oncology, Dana-Farber Cancer Institute, and Harvard Medical School, Boston; and Department of Pathology and Laboratory Medicine, University of Pennsylvania Medical Center, Philadelphia
| | - Robert B. Wilson
- Department of Pathology, Brigham and Women’s Hospital, Department of Adult Oncology, Dana-Farber Cancer Institute, and Harvard Medical School, Boston; and Department of Pathology and Laboratory Medicine, University of Pennsylvania Medical Center, Philadelphia
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